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Sample records for availability leaf life

  1. Plasticity as a plastic response: how submergence-induced leaf elongation in Rumex palustris depends on light and nutrient availability in its early life stage.

    PubMed

    Huber, Heidrun; Chen, Xin; Hendriks, Marloes; Keijsers, Danny; Voesenek, Laurentius A C J; Pierik, Ronald; Poorter, Hendrik; de Kroon, Hans; Visser, Eric J W

    2012-04-01

    Plants may experience different environmental cues throughout their development which interact in determining their phenotype. This paper tests the hypothesis that environmental conditions experienced early during ontogeny affect the phenotypic response to subsequent environmental cues. This hypothesis was tested by exposing different accessions of Rumex palustris to different light and nutrient conditions, followed by subsequent complete submergence. Final leaf length and submergence-induced plasticity were affected by the environmental conditions experienced at early developmental stages. In developmentally older leaves, submergence-induced elongation was lower in plants previously subjected to high-light conditions. Submergence-induced elongation of developmentally younger leaves, however, was larger when pregrown in high light. High-light and low-nutrient conditions led to an increase of nonstructural carbohydrates in the plants. There was a positive correlation between submergence-induced leaf elongation and carbohydrate concentration and content in roots and shoots, but not with root and shoot biomass before submergence. These results show that conditions experienced by young plants modulate the responses to subsequent environmental conditions, in both magnitude and direction. Internal resource status interacts with cues perceived at different developmental stages in determining plastic responses to the environment.

  2. Relationships of leaf dark respiration to leaf nitrogen, specific leaf area and leaf life-span: a test across biomes and functional groups

    Treesearch

    Peter B. Reich; Michael B. Walters; David S. Ellsworth; [and others; [Editor’s note: James M.. Vose is the SRS co-author for this publication.

    1998-01-01

    Based on prior evidence of coordinated multiple leaf trait scaling, the authors hypothesized that variation among species in leaf dark respiration rate (Rd) should scale with variation in traits such as leaf nitrogen (N), leaf life-span, specific leaf area (SLA), and net photosynthetic capacity (Amax). However, it is not known whether such scaling, if it exists, is...

  3. Leaf nitrogen and phosphorus of temperate desert plants in response to climate and soil nutrient availability.

    PubMed

    He, Mingzhu; Dijkstra, Feike A; Zhang, Ke; Li, Xinrong; Tan, Huijuan; Gao, Yanhong; Li, Gang

    2014-11-06

    In desert ecosystems, plant growth and nutrient uptake are restricted by availability of soil nitrogen (N) and phosphorus (P). The effects of both climate and soil nutrient conditions on N and P concentrations among desert plant life forms (annual, perennial and shrub) remain unclear. We assessed leaf N and P levels of 54 desert plants and measured the corresponding soil N and P in shallow (0-10 cm), middle (10-40 cm) and deep soil layers (40-100 cm), at 52 sites in a temperate desert of northwest China. Leaf P and N:P ratios varied markedly among life forms. Leaf P was higher in annuals and perennials than in shrubs. Leaf N and P showed a negative relationship with mean annual temperature (MAT) and no relationship with mean annual precipitation (MAP), but a positive relationship with soil P. Leaf P of shrubs was positively related to soil P in the deep soil. Our study indicated that leaf N and P across the three life forms were influenced by soil P. Deep-rooted plants may enhance the availability of P in the surface soil facilitating growth of shallow-rooted life forms in this N and P limited system, but further research is warranted on this aspect.

  4. Leaf nitrogen and phosphorus of temperate desert plants in response to climate and soil nutrient availability

    PubMed Central

    He, Mingzhu; Dijkstra, Feike A.; Zhang, Ke; Li, Xinrong; Tan, Huijuan; Gao, Yanhong; Li, Gang

    2014-01-01

    In desert ecosystems, plant growth and nutrient uptake are restricted by availability of soil nitrogen (N) and phosphorus (P). The effects of both climate and soil nutrient conditions on N and P concentrations among desert plant life forms (annual, perennial and shrub) remain unclear. We assessed leaf N and P levels of 54 desert plants and measured the corresponding soil N and P in shallow (0–10 cm), middle (10–40 cm) and deep soil layers (40–100 cm), at 52 sites in a temperate desert of northwest China. Leaf P and N:P ratios varied markedly among life forms. Leaf P was higher in annuals and perennials than in shrubs. Leaf N and P showed a negative relationship with mean annual temperature (MAT) and no relationship with mean annual precipitation (MAP), but a positive relationship with soil P. Leaf P of shrubs was positively related to soil P in the deep soil. Our study indicated that leaf N and P across the three life forms were influenced by soil P. Deep-rooted plants may enhance the availability of P in the surface soil facilitating growth of shallow-rooted life forms in this N and P limited system, but further research is warranted on this aspect. PMID:25373739

  5. Leaf acclimation to light availability supports rapid growth in tall Picea sitchensis trees.

    PubMed

    Chin, Alana R O; Sillett, Stephen C

    2017-03-21

    Leaf-level anatomical variation is readily apparent within tall tree crowns, yet the relative importance of water and light availability in controlling this variation remains unclear. Sitka spruce (Picea sitchensis, (Bong.) Carr.) thrives in temperate rainforests of the Pacific Northwest, where it has historically reached heights >100 m, despite rarely living more than 400 years alongside redwoods that are five times older. We examined leaves of trees up to 97 m tall using a combination of transverse sections, longitudinal sections, epidermal imprints and whole-leaf measurements to explore the combined effects of water stress and light availability on leaf development in P. sitchensis. In contrast to the situation in tall Cupressaceae, light availability-not hydraulic limitation-is the primary ecological driver of leaf-level anatomical variation in P. sitchensis. While height-associated decreases in leaf length and mesoporosity are best explained by hydrostatic constraints on leaf elongation, the majority of anatomical traits we measured reflect acclimation to light availability, including increases in leaf width and vascular tissue areas in the brightest parts of the crown. Along with these changes, the appearance of abaxial stomata in the bright upper crown, and the arrangement of mesophyll in uniseriate, transverse plates-with radially arranged apoplastic pathways leading directly to stomata before bridging them with a V-shaped cell-may enhance gas exchange and hydraulic conductivity. This suite of leaf traits suggests an adaptive strategy that maximizes photosynthesis at the expense of water-stress tolerance. Anatomical investigations spanning the height gradient in tall tree crowns build our understanding of mechanisms underlying among-species variation in growth rates, life spans, and potential responses to climate change. © The Author 2017. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  6. Optimal leaf-to-root ratio and leaf nitrogen content determined by light and nitrogen availabilities.

    PubMed

    Sugiura, Daisuke; Tateno, Masaki

    2011-01-01

    Plants exhibit higher leaf-to-root ratios (L/R) and lower leaf nitrogen content (N(area)) in low-light than in high-light environments, but an ecological significance of this trait has not been explained from a whole-plant perspective. This study aimed to theoretically and experimentally demonstrate whether these observed L/R and N(area) are explained as optimal biomass allocation that maximize whole-plant relative growth rate (RGR). We developed a model which predicts optimal L/R and N(area) in response to nitrogen and light availability. In the model, net assimilation rate (NAR) was determined by light-photosynthesis curve, light availability measured during experiments, and leaf temperature affecting the photosynthesis and leaf dark respiration rate in high and low-light environments. Two pioneer trees, Morus bombycis and Acer buergerianum, were grown in various light and nitrogen availabilities in an experimental garden and used for parameterizing and testing the model predictions. They were grouped into four treatment groups (relative photosynthetic photon flux density, RPPFD 100% or 10%×nitrogen-rich or nitrogen-poor conditions) and grown in an experimental garden for 60 to 100 days. The model predicted that optimal L/R is higher and N(area) is lower in low-light than high-light environments when compared in the same soil nitrogen availability. Observed L/R and N(area) of the two pioneer trees were close to the predicted optimums. From the model predictions and pot experiments, we conclude that the pioneer trees, M. bombycis and A. buergerianum, regulated L/R and N(area) to maximize RGR in response to nitrogen and light availability.

  7. Do initial S reserves and mineral S availability alter leaf S-N mobilization and leaf senescence in oilseed rape?

    PubMed

    Abdallah, M; Etienne, P; Ourry, A; Meuriot, F

    2011-03-01

    Winter oilseed rape is sensitive to S limitation, however few studies have clearly assessed the impact of initial S reserves on the remobilization of leaf N-S compounds and senescence dynamics within the leaves in S limited plants. As a consequence, the impacts of high or low initial S reserves on these parameters, further cross-combined with either high or low S availabilities, were examined using a ¹⁵N and ³⁴S double-labelling method associated with a study of gene expression of relevant tonoplastic sulphate transporters (BnSultr4;1 and BnSultr4;2) and a molecular indicator of leaf senescence (BnSAG12/BnCab). Plants with high initial S status and S limitation showed an optimal growth comparable to control plants. Moreover, in response to S limitation, leaf soluble protein content, total S, recently assimilated S (i.e., ³⁴S) and the sulphate content in the oldest leaves declined, and the expression of genes encoding tonoplastic sulphate transporters were up-regulated. However, compared to control plants, S limitation delayed leaf senescence. These data suggested that in response to S limitation, plants with high initial S were able to sustain optimized leaf growth by increasing endogenous N and S remobilization independently of the leaf senescence process. In contrast, if these low S plants had no initial S reserves, leaf N-S remobilization was not sufficient to allow optimal growth. As a conclusion, our study supports a model where oilseed rape is able to compensate transiently for S limitation through a fine management of leaf N-S remobilization and a delayed leaf senescence dynamics.

  8. MAKING LIFE CYCLE INVENTORY DATA AVAILABLE

    EPA Science Inventory

    Making Life Cycle Inventory Data Available

    Mary Ann Curran
    US EPA, National Risk Management Research Laboratory
    Address: 26 W. Martin Luther King Drive (MS-466)
    Cincinnati, OH 45268 USA
    Phone: 513-569-7782
    Fax: 513-569-7111
    E-Mail: curran.maryann@...

  9. MAKING LIFE CYCLE INVENTORY DATA AVAILABLE

    EPA Science Inventory

    Making Life Cycle Inventory Data Available

    Mary Ann Curran
    US EPA, National Risk Management Research Laboratory
    Address: 26 W. Martin Luther King Drive (MS-466)
    Cincinnati, OH 45268 USA
    Phone: 513-569-7782
    Fax: 513-569-7111
    E-Mail: curran.maryann@...

  10. Influence of light availability on leaf structure and growth of two Eucalyptus globulus ssp. globulus provenances.

    PubMed

    James, S A; Bell, D T

    2000-09-01

    Light availability strongly affects leaf structure of the distinctive ontogenetic leaf forms of Eucalyptus globulus Labill. ssp. globulus. Late-maturing plants from St. Marys, Tasmania and early maturing plants from Wilsons Promontory, Victoria (hereafter referred to as Wilsons Prom.) were grown for 9 months in 100, 50 or 10% sunlight. Growth, biomass and leaf area were significantly reduced when plants were grown in 10% sunlight. Provenance differences were minimal despite retention of the juvenile leaf form by the Tasmanian plants throughout the study. The time taken for initiation of vegetative phase change by the Wilsons Prom. saplings increased with decreasing light availability, but the nodal position of change on the main stem remained the same. Both juvenile and adult leaves remained horizontal in low light conditions, but became vertical with high irradiance. Leaf dimensions changed with ontogenetic development, but were unaffected by light availability. Juvenile leaves retained a dorsiventral anatomy and adult Wilsons Prom. leaves retained an isobilateral structure despite a tenfold difference in light availability. Stomatal density and distribution showed ontogenetic and treatment differences. At all irradiances, juvenile leaves produced the smallest stomata and adult leaves the largest stomata. Amphistomy decreased with decreasing irradiance. Detrended, correspondence analysis ordination highlighted the structural changes influenced by ontogenetic development and light availability. Adult leaves had characteristics similar to the xeromorphic, sun-leaf type found in arid, high-light conditions. Although juvenile leaves had characteristics typical of mesomorphic leaves, several structural features suggest that these leaves are more sun-adapted than adult leaves.

  11. Do seasonal changes in light availability influence the inverse leafing phenology of the neotropical dry forest understory shrub Bonellia nervosa (Theophrastaceae)?

    PubMed

    Chaves, Oscar M; Avalos, Gerardo

    2008-03-01

    In tropical dry forests most plants are deciduous during the dry season and flush leaves with the onset of the rains. In Costa Rica, the only species displaying the opposite pattern is Bonellia nervosa. To determine if seasonal changes in light availability are associated with the leaf and reproductive phenology of this species, we monitored leaf production, survival, and life span, as well as flower and fruit production from April 2000 to October 2001 in Santa Rosa National Park. Leaf flushing and flower bud production took place shortly after the autumnal equinox when day length starts to decrease. Leaves began expansion at the end of the wet season, and plants reached 70 % of their maximum leaf area at the beginning of the dry season, maintaining their foliage throughout the entire dry period. Leaf shedding occurred gradually during the first three months of the wet season. Leaf flushing and shedding showed high synchrony, with leaf numbers being related to light availability. Maximum leaf production coincided with peaks in radiation during the middle of the dry season. Decreasing day length induces highly synchronous flower bud emergence in dry forest species, but this is the first study indicating induction of leaf flushing by declining day length.

  12. Interspecific vs intraspecific patterns in leaf nitrogen of forest trees across nitrogen availability gradients.

    PubMed

    Dybzinski, Ray; Farrior, Caroline E; Ollinger, Scott; Pacala, Stephen W

    2013-10-01

    Leaf nitrogen content (δ) coordinates with total canopy N and leaf area index (LAI) to maximize whole-crown carbon (C) gain, but the constraints and contributions of within-species plasticity to this phenomenon are poorly understood. Here, we introduce a game theoretic, physiologically based community model of height-structured competition between late-successional tree species. Species are constrained by an increasing, but saturating, relationship between photosynthesis and leaf N per unit leaf area. Higher saturating rates carry higher fixed costs. For a given whole-crown N content, a C gain-maximizing compromise exists between δ and LAI. With greater whole-crown N, both δ and LAI increase within species. However, a shift in community composition caused by reduced understory light at high soil N availability (which competitively favors species with low leaf costs and consequent low optimal δ) counteracts the within-species response, such that community-level δ changes little with soil N availability. These model predictions provide a new explanation for the changes in leaf N per mass observed in data from three dominant broadleaf species in temperate deciduous forests of New England. Attempts to understand large-scale patterns in vegetation often omit competitive interactions and intraspecific plasticity, but here both are essential to an understanding of ecosystem-level patterns.

  13. Leaf life span plasticity in tropical seedlings grown under contrasting light regimes.

    PubMed

    Vincent, Gregoire

    2006-02-01

    The phenotypic plasticity of leaf life span in response to low resource conditions has a potentially large impact on the plant carbon budget, notably in evergreen species not subject to seasonal leaf shedding, but has rarely been well documented. This study evaluates the plasticity of leaf longevity, in terms of its quantitative importance to the plant carbon balance under limiting light. Seedlings of four tropical tree species with contrasting light requirements (Alstonia scholaris, Hevea brasiliensis, Durio zibethinus and Lansium domesticum) were grown under three light regimes (full sunlight, 45 % sunlight and 12 % sunlight). Their leaf dynamics were monitored over 18 months. All species showed a considerable level of plasticity with regard to leaf life span: over the range of light levels explored, the ratio of the range to the mean value of life span varied from 29 %, for the least plastic species, to 84 %, for the most. The common trend was for leaf life span to increase with decreasing light intensity. The plasticity apparent in leaf life span was similar in magnitude to the plasticity observed in specific leaf area and photosynthetic rate, implying that it has a significant impact on carbon gain efficiency when plants acclimate to different light regimes. In all species, median survival time was negatively correlated with leaf photosynthetic capacity (or its proxy, the nitrogen content per unit area) and leaf emergence rate. Longer leaf life spans under low light are likely to be a consequence of slower ageing as a result of a slower photosynthetic metabolism.

  14. Estimation of shrub leaf biomass available to white-tailed deer.

    Treesearch

    Lynn L. Rogers; Ronald E. McRoberts

    1992-01-01

    Describes an objective method for using shrub height to estimate leaf biomass within reach of deer. The method can be used in conjunction with surveys of shrub height, shrub density, and shrub species composition to evaluate deer habitat over large areas and to predict trends in forage availability with further forest growth.

  15. Phosphorus availability modulates the toxic effect of silver on aquatic fungi and leaf litter decomposition.

    PubMed

    Funck, J Arce; Clivot, H; Felten, V; Rousselle, P; Guérold, F; Danger, M

    2013-11-15

    The functioning of forested headwater streams is intimately linked to the decomposition of leaf litter by decomposers, mainly aquatic hyphomycetes, which enables the transfer of allochthonous carbon to higher trophic levels. Evaluation of this process is being increasingly used as an indicator of ecosystem health and ecological integrity. Yet, even though the individual impacts of contaminants and nutrient availability on decomposition have been well studied, the understanding of their combined effects remains limited. In the current study, we investigated whether the toxic effects of a reemerging contaminant, silver (Ag), on leaf litter decomposition could be partly overcome in situations where microorganisms were benefitting from high phosphorus (P) availability, the latter being a key chemical element that often limits detritus decomposition. We also investigated whether these interactive effects were mediated by changes in the structure of the aquatic hyphomycete community. To verify these hypotheses, leaf litter decomposition by a consortium of ten aquatic hyphomycete species was followed in a microcosm experiment combining five Ag contamination levels and three P concentrations. Indirect effects of Ag and P on the consumption of leaf litter by the detritivorous crustacean, Gammarus fossarum, were also evaluated. Ag significantly reduced decomposition but only at the highest concentration tested, independently of P level. By contrast, P and Ag interactively affected fungal biomass. Both P level and Ag concentrations shaped microbial communities without significantly affecting the overall species richness. Finally, the levels of P and Ag interacted significantly on G. fossarum feeding rates, high [Ag] reducing litter consumption and low P availability tending to intensify the feeding rate. Given the high level of contaminant needed to impair the decomposition process, it is unlikely that a direct effect of Ag on leaf litter decomposition could be observed in

  16. Leaf Life Span Plasticity in Tropical Seedlings Grown under Contrasting Light Regimes

    PubMed Central

    VINCENT, GREGOIRE

    2006-01-01

    • Background and Aims The phenotypic plasticity of leaf life span in response to low resource conditions has a potentially large impact on the plant carbon budget, notably in evergreen species not subject to seasonal leaf shedding, but has rarely been well documented. This study evaluates the plasticity of leaf longevity, in terms of its quantitative importance to the plant carbon balance under limiting light. • Methods Seedlings of four tropical tree species with contrasting light requirements (Alstonia scholaris, Hevea brasiliensis, Durio zibethinus and Lansium domesticum) were grown under three light regimes (full sunlight, 45 % sunlight and 12 % sunlight). Their leaf dynamics were monitored over 18 months. • Results All species showed a considerable level of plasticity with regard to leaf life span: over the range of light levels explored, the ratio of the range to the mean value of life span varied from 29 %, for the least plastic species, to 84 %, for the most. The common trend was for leaf life span to increase with decreasing light intensity. The plasticity apparent in leaf life span was similar in magnitude to the plasticity observed in specific leaf area and photosynthetic rate, implying that it has a significant impact on carbon gain efficiency when plants acclimate to different light regimes. In all species, median survival time was negatively correlated with leaf photosynthetic capacity (or its proxy, the nitrogen content per unit area) and leaf emergence rate. • Conclusions Longer leaf life spans under low light are likely to be a consequence of slower ageing as a result of a slower photosynthetic metabolism. PMID:16299004

  17. Effect of Assembly Stresses on Fatigue Life of Symmetrical 65Si7 Leaf Springs

    PubMed Central

    Arora, Vinkel Kumar; Bhushan, Gian; Aggarwal, M. L.

    2014-01-01

    The maximum stress induced plays vital role in fatigue life improvement of leaf springs. To reduce this maximum stress, leaves with different unassembled cambers are assembled by pulling against each other and a common curvature is established. This causes stress concentration or sets assembly stress in the assembled leaf springs which is subtractive from load stress in master leaf while it is additive to load stress for short leaves. By suitable combination of assembly stresses and stepping, it is possible to distribute the stress and improve the fatigue life of the leaf spring. The effect of assembly stresses on fatigue life of the leaf spring of a light commercial vehicle (LCV) has been studied. A proper combination of stepping and camber has been proposed by taking the design parameters into consideration, so that the stress in the leaves does not exceed maximum design stress. The theoretical fatigue life of the leaf springs with and without considering the assembly stresses is determined and compared with experimental life. The numbers of specimens are manufactured with proposed parameters and tested for load rate, fatigue life on a full scale leaf springs testing machine. The effect of stress range, maximum stress, and initial stress is also discussed. PMID:27433537

  18. Fatigue Life Assessment of 65Si7 Leaf Springs: A Comparative Study

    PubMed Central

    Arora, Vinkel Kumar; Bhushan, Gian; Aggarwal, M. L.

    2014-01-01

    The experimental fatigue life prediction of leaf springs is a time consuming process. The engineers working in the field of leaf springs always face a challenge to formulate alternate methods of fatigue life assessment. The work presented in this paper provides alternate methods for fatigue life assessment of leaf springs. A 65Si7 light commercial vehicle leaf spring is chosen for this study. The experimental fatigue life and load rate are determined on a full scale leaf spring testing machine. Four alternate methods of fatigue life assessment have been depicted. Firstly by SAE spring design manual approach the fatigue test stroke is established and by the intersection of maximum and initial stress the fatigue life is predicted. The second method constitutes a graphical method based on modified Goodman's criteria. In the third method codes are written in FORTRAN for fatigue life assessment based on analytical technique. The fourth method consists of computer aided engineering tools. The CAD model of the leaf spring has been prepared in solid works and analyzed using ANSYS. Using CAE tools, ideal type of contact and meshing elements have been proposed. The method which provides fatigue life closer to experimental value and consumes less time is suggested. PMID:27379327

  19. Leaf life span spectrum of tropical woody seedlings: effects of light and ontogeny and consequences for survival

    PubMed Central

    Kitajima, Kaoru; Cordero, Roberto A.; Wright, S. Joseph

    2013-01-01

    Background and Aims Leaf life span is widely recognized as a key life history trait associated with herbivory resistance, but rigorous comparative data are rare for seedlings. The goal of this study was to examine how light environment affects leaf life span, and how ontogenetic development during the first year may influence leaf fracture toughness, lamina density and stem density that are relevant for herbivory resistance, leaf life span and seedling survival. Methods Data from three experiments encompassing 104 neotropical woody species were combined. Leaf life span, lamina and vein fracture toughness, leaf and stem tissue density and seedling survival were quantified for the first-year seedlings at standardized ontogenetic stages in shade houses and common gardens established in gaps and shaded understorey in a moist tropical forest in Panama. Mortality of naturally recruited seedlings till 1 year later was quantified in 800 1-m2 plots from 1994 to 2011. Key Results Median leaf life span ranged widely among species, always greater in shade (ranging from 151 to >1790 d in the understorey and shade houses) than in gaps (115–867 d), but with strong correlation between gaps and shade. Leaf and stem tissue density increased with seedling age, whereas leaf fracture toughness showed only a weak increase. All these traits were positively correlated with leaf life span. Leaf life span and stem density were negatively correlated with seedling mortality in shade, while gap mortality showed no correlation with these traits. Conclusions The wide spectrum of leaf life span and associated functional traits reflects variation in shade tolerance of first-year seedlings among coexisting trees, shrubs and lianas in this neotropical forest. High leaf tissue density is important in enhancing leaf toughness, a known physical defence, and leaf life span. Both seedling leaf life span and stem density should be considered as key functional traits that contribute to seedling survival

  20. Leaf hydraulic vulnerability to drought is linked to site water availability across a broad range of species and climates

    PubMed Central

    Blackman, Chris J.; Gleason, Sean M.; Chang, Yvonne; Cook, Alicia M.; Laws, Claire; Westoby, Mark

    2014-01-01

    Background and Aims Vulnerability of the leaf hydraulic pathway to water-stress-induced dysfunction is a key component of drought tolerance in plants and may be important in defining species' climatic range. However, the generality of the association between leaf hydraulic vulnerability and climate across species and sites remains to be tested. Methods Leaf hydraulic vulnerability to drought (P50leaf, the water potential inducing 50 % loss in hydraulic function) was measured in a diverse group of 92 woody, mostly evergreen angiosperms from sites across a wide range of habitats. These new data together with some previously published were tested against key climate indices related to water availability. Differences in within-site variability in P50leaf between sites were also examined. Key Results Values of hydraulic vulnerability to drought in leaves decreased strongly (i.e. became more negative) with decreasing annual rainfall and increasing aridity across sites. The standard deviation in P50leaf values recorded within each site was positively correlated with increasing aridity. P50leaf was also a good indicator of the climatic envelope across each species' distributional range as well as their dry-end distributional limits within Australia, although this relationship was not consistently detectable within sites. Conclusions The findings indicate that species sorting processes have influenced distributional patterns of P50leaf across the rainfall spectrum, but alternative strategies for dealing with water deficit exist within sites. The strong link to aridity suggests leaf hydraulic vulnerability may influence plant distributions under future climates. PMID:25006181

  1. Flood flows, leaf breakdown, and plant-available nitrogen on a dryland river floodplain

    USGS Publications Warehouse

    Andersen, Douglas C.; Nelson, S. Mark; Binkley, Dan

    2003-01-01

    We tested the hypothesis that decomposition in flood-inundated patches of riparian tree leaf litter results in higher plant-available nitrogen in underlying, nutrient-poor alluvium. We used leafpacks (n = 56) containing cottonwood (Populus deltoides ssp. wislizenii) leaf litter to mimic natural accumulations of leaves in an experiment conducted on the Yampa River floodplain in semi-arid northwestern Colorado, USA. One-half of the leafpacks were set on the sandy alluvial surface, and one-half were buried 5 cm below the surface. The presence of NO3− and NH4+ presumed to result from a leafpack's submergence during the predictable spring flood pulse was assessed using an ion-exchange resin bag (IER) placed beneath each leafpack and at control locations. Leafpacks and IERs were collected one week after flood peak (71 days total exposure) at half the stations; the remainder were collected three weeks later (93 days exposure). A multi-peaked spring flood with above-average maximum discharge inundated leafpacks for total time periods ranging from 133 to 577 hours. Litter lost from 43 to 68 percent of its initial organic matter (OM) content. Organic matter loss increased with total time inundated and total time of exposure on the floodplain. Burial retarded OM loss if the total time inundated was relatively long, and substrate texture (sand vs. silt) affected OM loss in a complex manner through interactions with total time inundated and total time of exposure. No pulse of N attributable to leaf breakdown was detected in the IERs, and leafpack litter showed no net change in the mass of nitrogen present. Patterns of leafpack and IER nitrogen levels suggested that litter removed N from floodwater and thereby reduced N availability in underlying sediment. Immobilization of floodwater-N by litter and N mineralization outside the flood period may be important components of N flux in semi-arid and arid floodplain environments.

  2. An Examination of Operational Availability in Life Cycle Cost Models

    DTIC Science & Technology

    1983-09-01

    necessary and identify by block number) Life Cycle Cost Management Reliability Life Cycle Cost Model Maintainability Availability Supportability...availability and the relative cost for those levels. 2 The analytical models must go beyond individual parameters of reliability and maintainability (R&M...availability is a function of reliability and maintainability (R&M) (3:20). The two terms that comprise the function are defined here. Reliability : The

  3. Climate and host plant availability impact the future distribution of the bean leaf beetle (Cerotoma trifurcata).

    PubMed

    Berzitis, Emily A; Minigan, Jordan N; Hallett, Rebecca H; Newman, Jonathan A

    2014-09-01

    The bean leaf beetle, Cerotoma trifurcata, has become a major pest of soybean throughout its North American range. With a changing climate, there is the potential for this pest to further expand its distribution and become an increasingly severe pest in certain regions. To examine this possibility, we developed bioclimatic envelope models for both the bean leaf beetle, and its most important agronomic host plant, soybean (Glycine max). These two models were combined to examine the potential future pest status of the beetle using climate change projections from multiple general circulation models (GCMs) and climate change scenarios. Despite the broad tolerances of soybean, incorporation of host plant availability substantially decreased the suitable and favourable areas for the bean leaf beetle as compared to an evaluation based solely on the climate envelope of the beetle, demonstrating the importance of incorporating biotic interactions in these predictions. The use of multiple GCM-scenario combinations also revealed differences in predictions depending on the choice of GCM, with scenario choice having less of an impact. While the Norwegian model predicted little northward expansion of the beetle from its current northern range limit of southern Ontario and overall decreases in suitable and favourable areas over time, the Canadian and Russian models predict that much of Ontario and Quebec will become suitable for the beetle in the future, as well as Manitoba under the Russian model. The Russian model also predicts expansion of the suitable and favourable areas for the beetle over time. Two predictions that do not depend on our choice of GCM include a decrease in suitability of the Mississippi Delta region and continued favourability of the southeastern United States.

  4. Psidium guajava and Piper betle Leaf Extracts Prolong Vase Life of Cut Carnation (Dianthus caryophyllus) Flowers

    PubMed Central

    Rahman, M. M.; Ahmad, S. H.; Lgu, K. S.

    2012-01-01

    The effect of leaf extracts of Psidium guajava and Piper betle on prolonging vase life of cut carnation flowers was studied. “Carola” and “Pallas Orange” carnation flowers, at bud stage, were pulsed 24 hours with a floral preservative. Then, flowers were placed in a vase solution containing sprite and a “germicide” (leaf extracts of P. guajava and P. betle, 8-HQC, or a copper coin). Flowers treated with 8-HQC, copper coin, and leaf extracts had longer vase life, larger flower diameter, and higher rate of water uptake compared to control (tap water). The leaf extracts of P. guajava and P. betle showed highest antibacterial and antifungal activities compared to the other treatments. Both showed similar effects on flower quality as the synthetic germicide, 8-HQC. Therefore, these extracts are likely natural germicides to prolong vase life of cut flowers. PMID:22619568

  5. Psidium guajava and Piper betle leaf extracts prolong vase life of cut carnation (Dianthus caryophyllus) flowers.

    PubMed

    Rahman, M M; Ahmad, S H; Lgu, K S

    2012-01-01

    The effect of leaf extracts of Psidium guajava and Piper betle on prolonging vase life of cut carnation flowers was studied. "Carola" and "Pallas Orange" carnation flowers, at bud stage, were pulsed 24 hours with a floral preservative. Then, flowers were placed in a vase solution containing sprite and a "germicide" (leaf extracts of P. guajava and P. betle, 8-HQC, or a copper coin). Flowers treated with 8-HQC, copper coin, and leaf extracts had longer vase life, larger flower diameter, and higher rate of water uptake compared to control (tap water). The leaf extracts of P. guajava and P. betle showed highest antibacterial and antifungal activities compared to the other treatments. Both showed similar effects on flower quality as the synthetic germicide, 8-HQC. Therefore, these extracts are likely natural germicides to prolong vase life of cut flowers.

  6. Quantifying plant age and available water effects on soybean leaf conductance

    USDA-ARS?s Scientific Manuscript database

    In this study, we present data characterizing the effects of soil moisture levels on total leaf conductance for two distinct determinate soybean (Glycine max (L.) Merr.) genotypes and subsequently use these data to formulate and validate a model that characterizes total leaf conductance. Conductanc...

  7. Leaf hydraulic vulnerability to drought is linked to site water availability across a broad range of species and climates.

    PubMed

    Blackman, Chris J; Gleason, Sean M; Chang, Yvonne; Cook, Alicia M; Laws, Claire; Westoby, Mark

    2014-09-01

    Vulnerability of the leaf hydraulic pathway to water-stress-induced dysfunction is a key component of drought tolerance in plants and may be important in defining species' climatic range. However, the generality of the association between leaf hydraulic vulnerability and climate across species and sites remains to be tested. Leaf hydraulic vulnerability to drought (P50leaf, the water potential inducing 50 % loss in hydraulic function) was measured in a diverse group of 92 woody, mostly evergreen angiosperms from sites across a wide range of habitats. These new data together with some previously published were tested against key climate indices related to water availability. Differences in within-site variability in P50leaf between sites were also examined. Values of hydraulic vulnerability to drought in leaves decreased strongly (i.e. became more negative) with decreasing annual rainfall and increasing aridity across sites. The standard deviation in P50leaf values recorded within each site was positively correlated with increasing aridity. P50leaf was also a good indicator of the climatic envelope across each species' distributional range as well as their dry-end distributional limits within Australia, although this relationship was not consistently detectable within sites. The findings indicate that species sorting processes have influenced distributional patterns of P50leaf across the rainfall spectrum, but alternative strategies for dealing with water deficit exist within sites. The strong link to aridity suggests leaf hydraulic vulnerability may influence plant distributions under future climates. © The Author 2014. Published by Oxford University Press on behalf of the Annals of Botany Company. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  8. Several aspects of cultivating leaf greens in bioregenerative life support systems

    NASA Astrophysics Data System (ADS)

    Levinskikh, M. A.; Podolsky, I. G.; Sychev, V. N.

    Available results of theoretical and empirical studies of closed eco-systems lay the ground for the common opinion concerning desirability of incorporating higher plant cultivation equipment in the life support systems of closed habitats of varying purpose (space stations, Martian expedition, hyperbaric complexes in deep waters etc.) in order to add fresh greens to food rations, regenerate air and water, and to better the psychological climate. Design and functional features of this equipment and choice of plants are determined by the dimensions of habitat, power generation, length of self-sustained existence beyond Earth's biosphere and other factors. We are going to consider a particular case of fresh green biomass production for space crew nutrition with limited size and energy resources. The paper presents results of ground and space experimental investigations of a number of aspects of cultivating leaf plant species as applied to research and productive greenhouses. Goals of the investigations were to prepare for flight experiments in greenhouses LADA aboard ISS, and determination of specifications for future productive greenhouses for a Martian mission and its prototyping in ground-based simulations. The following objectives were pursued: - selection of the seeding surface shape and spatial configuration of productive and research greenhouses that can be proposed for the orbital station or a Martian vehicle comparison of productivity of leaf greens cultivated on different substrates; - determination of the maximal plant biomass yield and number of crops that can be gathered from root module without substrate change; - choice of leaf culture cultivars and species featured by very quick biomass buildup and pleasant taste qualities.

  9. Herbivores sculpt leaf traits differently in grasslands depending on life form and land-use histories.

    PubMed

    Firn, Jennifer; Schütz, Martin; Nguyen, Huong; Risch, Anita C

    2017-01-01

    Vertebrate and invertebrate herbivores alter plant communities directly by selectively consuming plant species; and indirectly by inducing morphological and physiological changes to plant traits that provide competitive or survivorship advantages to some life forms over others. Progressively excluding aboveground herbivore communities (ungulates, medium and small sized mammals, invertebrates) over five growing seasons, we explored how leaf morphology (specific leaf area or SLA) and nutrition (nitrogen, carbon, phosphorous, potassium, sodium, and calcium) of different plant life forms (forbs, legumes, grasses, sedges) correlated with their dominance. We experimented in two subalpine grassland types with different land-use histories: (1) heavily grazed, nutrient-rich, short-grass vegetation and (2) lightly grazed, lower nutrient tall-grass vegetation. We found differences in leaf traits between treatments where either all herbivores were excluded or all herbivores were present, showing the importance of considering the impacts of both vertebrates and invertebrates on the leaf traits of plant species. Life forms responses to the progressive exclusion of herbivores were captured by six possible combinations: (1) increased leaf size and resource use efficiency (leaf area/nutrients) where lower nutrient levels are invested in leaf construction, but a reduction in the number of leaves, for example, forbs in both vegetation types, (2) increased leaf size and resource use efficiency, for example, legumes in short grass, (3) increased leaf size but a reduction in the number of leaves, for example, legumes in the tall grass, (4) increased number of leaves produced and increased resource use efficiency, for example, grasses in the short grass, (5) increased resource use efficiency of leaves only, for example, grasses and sedges in the tall grass, and (6) no response in terms of leaf construction or dominance, for example, sedges in the short grass. Although we found multiple

  10. Leaf Mass per Area (LMA) and Its Relationship with Leaf Structure and Anatomy in 34 Mediterranean Woody Species along a Water Availability Gradient.

    PubMed

    de la Riva, Enrique G; Olmo, Manuel; Poorter, Hendrik; Ubera, José Luis; Villar, Rafael

    2016-01-01

    Leaf mass per area (LMA) is a morphological trait widely used as a good indicator of plant functioning (i.e. photosynthetic and respiratory rates, chemical composition, resistance to herbivory, etc.). The LMA can be broken down into the leaf density (LD) and leaf volume to area ratio (LVA or thickness), which in turn are determined by anatomical tissues and chemical composition. The aim of this study is to understand the anatomical and chemical characteristics related to LMA variation in species growing in the field along a water availability gradient. We determined LMA and its components (LD, LVA and anatomical tissues) for 34 Mediterranean (20 evergreen and 14 deciduous) woody species. Variation in LMA was due to variation in both LD and LVA. For both deciduous and evergreen species LVA variation was strongly and positively related with mesophyll volume per area (VA or thickness), but for evergreen species positive relationships of LVA with the VA of epidermis, vascular plus sclerenchyma tissues and air spaces were found as well. The leaf carbon concentration was positively related with mesophyll VA in deciduous species, and with VA of vascular plus sclerenchymatic tissues in evergreens. Species occurring at the sites with lower water availability were generally characterised by a high LMA and LD.

  11. Leaf Mass per Area (LMA) and Its Relationship with Leaf Structure and Anatomy in 34 Mediterranean Woody Species along a Water Availability Gradient

    PubMed Central

    de la Riva, Enrique G.; Olmo, Manuel; Poorter, Hendrik; Ubera, José Luis; Villar, Rafael

    2016-01-01

    Leaf mass per area (LMA) is a morphological trait widely used as a good indicator of plant functioning (i.e. photosynthetic and respiratory rates, chemical composition, resistance to herbivory, etc.). The LMA can be broken down into the leaf density (LD) and leaf volume to area ratio (LVA or thickness), which in turn are determined by anatomical tissues and chemical composition. The aim of this study is to understand the anatomical and chemical characteristics related to LMA variation in species growing in the field along a water availability gradient. We determined LMA and its components (LD, LVA and anatomical tissues) for 34 Mediterranean (20 evergreen and 14 deciduous) woody species. Variation in LMA was due to variation in both LD and LVA. For both deciduous and evergreen species LVA variation was strongly and positively related with mesophyll volume per area (VA or thickness), but for evergreen species positive relationships of LVA with the VA of epidermis, vascular plus sclerenchyma tissues and air spaces were found as well. The leaf carbon concentration was positively related with mesophyll VA in deciduous species, and with VA of vascular plus sclerenchymatic tissues in evergreens. Species occurring at the sites with lower water availability were generally characterised by a high LMA and LD. PMID:26867213

  12. Comparative leaf growth strategies in response to low-water and low-light availability: variation in leaf physiology underlies variation in leaf mass per area in Populus tremuloides.

    PubMed

    Baird, Alec S; Anderegg, Leander D L; Lacey, Melissa E; HilleRisLambers, Janneke; Van Volkenburgh, Elizabeth

    2017-04-04

    Developmental phenotypic plasticity can allow plants to buffer the effects of abiotic and biotic environmental stressors. Therefore, it is vital to improve our understanding of how phenotypic plasticity in ecological functional traits is coordinated with variation in physiological performance in plants. To identify coordinated leaf responses to low-water (LW) versus low-light (LL) availability, we measured leaf mass per area (LMA), leaf anatomical characteristics and leaf gas exchange of juvenile Populus tremuloides Michx. trees. Spongy mesophyll tissue surface area (Asmes/A) was correlated with intrinsic water-use efficiency (WUEi: photosynthesis, (Aarea)/stomatal conductance (gs)). Under LW availability, these changes occurred at the cost of greater leaf tissue density and reduced expansive growth, as leaves were denser but were only 20% the final area of control leaves, resulting in elevated LMA and elevated WUEi. Low light resulted in reduced palisade mesophyll surface area (Apmes/A) while spongy mesophyll surface area was maintained (Asmes/A), with no changes to WUEi. These leaf morphological changes may be a plastic strategy to increase laminar light capture while maintaining WUEi. With reduced density and thickness, however, leaves were 50% the area of control leaves, ultimately resulting in reduced LMA. Our results illustrate that P. tremuloides saplings partially maintain physiological function in response to water and light limitation by inducing developmental plasticity in LMA with underlying anatomical changes. We discuss additional implications of these results in the context of developmental plasticity, growth trade-offs and the ecological impacts of climate change.

  13. Inconsistent intraspecific pattern in leaf life span along nitrogen-supply gradient.

    PubMed

    Oikawa, Shimpei; Suno, Koya; Osada, Noriyuki

    2017-02-01

    Leaf life span (LLS) has long been hypothesized to plastically increase with decreasing nitrogen (N) supply from soil to maximize N retention, carbon assimilation, and fitness; however, accumulating evidence shows no consistent trend. The apparent inconsistencies are explained by a recent model that assumes LLS has a hump-shaped quadratic response to the N-supply gradient. The available evidence mostly originates from comparisons of LLS at only two levels of N availability, and the hypothesis remains unanswered. We investigated LLS of two asteraceous forbs (Adenocaulon himalaicum and Xanthium canadense) experimentally grown at eight levels of N supply, which covered a range of N supply in their natural habitats. We additionally conducted a literature search to retrieve studies reporting LLS response along an N-supply gradient. The LLS of neither species showed a hump-shaped response along the N-supply gradient. Past studies examining the LLS of an aquatic forb and terrestrial shrubs and trees along the N-supply gradient (more than four levels of N supply) also refuted the hypothesis. The LLS of a single species exhibited neither an increase nor a hump-shaped response to decreased N supply in a variety of life forms. Comparisons at only a few N levels are misleading with regard to LLS response to N supply. © 2017 Botanical Society of America.

  14. Leaf life span and the mobility of "non-mobile" mineral nutrients - the case of boron in conifers

    Treesearch

    Pedro J. Aphalo; Anna W. Schoettle; Tarja Lehto

    2002-01-01

    Nutrient conservation is considered important for the adaptation of plants to infertile environments. The importance of leaf life spans in controlling mean residence time of nutrients in plants has usually been analyzed in relation to nutrients that can be retranslocated within the plant. Longer leaf life spans increase the mean residence time of all mineral...

  15. [Life form spectra, leaf character, and hierarchical-synusia structure of vascular plants in Thuja sutchuehensis community].

    PubMed

    Guo, Quan-shui; Wang, Xiang-fu; Bar, Guli; Kang, Yi; Hong, Ming; Pei, Shun-xiang; Zhang, Fa-jun

    2009-09-01

    Based on the investigation of the plants in Thuja sutchuenensis community, the life form spectra, leaf character, and hierarchical-synusia structure in the community were analyzed. The life form spectra of the plants in the community were 73.2% of phanemphyte, 18% of hemicryptophyte, 6% of geophyte, 2% of chamaephyte, and 0.8% of annual plants. The leaf quality was mainly of papery and conaceous, which occupied 48. 8% and 36. 4% , respectively. The dominant leaf size was microphy (60.8%), dominant leaf margin was un-entire (56.8%), and dominant leaf form was simple (86%). The T. sutchuenensis community had three sub-layers, i.e., tree layer, shrub layer, and herb layer, with lesser interlayer plants. Each layer was respectively composed by phanemphyte evergreen coniferophyte, broadleaf and deciduous broad-leaf plants, nanophanerophyte evergreen and deciduous broad-leaf plants, as well as hemicryptophyte, geophyte, and annual plants.

  16. Modelling sugar diffusion across plant leaf cuticles: the effect of free water on substrate availability to phyllosphere bacteria.

    PubMed

    van der Wal, Annemieke; Leveau, Johan H J

    2011-03-01

    We present a continuous model for the diffusion of sugars across intact plant leaf cuticles. It is based on the flow of sugars from a source, representing the leaf apoplast, to a sink, in the shape of a hemispherical drop of water on the outside of the cuticle. Flow is a function of the difference between sugar concentrations C(Source) and C(Sink) , permeability P of the cuticle, volume V(Sink) of the water drop, as well as its contact angle α with the cuticle surface. Using a bacterial bioreporter for fructose, and a two-compartment experimental set-up consisting of isolated cuticles of walnut (Juglans regia) carrying water droplets while floating on solutions with increasing concentrations of fructose, we determined a value of 1 × 10⁻⁶ m h⁻¹ for P. Using this value, we explored different scenarios for the leaching of sugars across plant leaf cuticles to reveal in quantitative terms how diffusion takes longer when V(Sink) increases, P decreases or α increases. Bacterial growth was modelled as a function of changes in P, α and V(Sink) and was consistent with observations or suggestions from the literature in relation to the availability of free water on leaves. These results are discussed in the light of bacteria as ecosystem engineers, i.e. with the ability to modify the plant leaf surface environment in favour of their own survival, e.g. by increasing cuticle leakage or leaf wetness. Our model represents a first step towards a more comprehensive model which will enhance our quantitative understanding of the factors that play a role in nutrient availability to bacterial colonizers of the phyllosphere, or plant leaf surface. © 2010 Society for Applied Microbiology and Blackwell Publishing Ltd.

  17. Causes and consequences of variation in conifer leaf life-span

    SciTech Connect

    Reich, P.B.; Koike, T.; Gower, S.T.; Schoettle, A.W.

    1995-07-01

    Species with mutually supporting traits, such as high N{sub mass}, SLA, and A{sub mass}, and short leaf life-span, tend to inhabit either generally resource-rich environments or spatial and/or temporal microhabitats that are resource-rich in otherwise more limited habitats (e.g., {open_quotes}precipitation{close_quotes} ephemerals in warm deserts or spring ephemerals in the understory of temperate deciduous forests). In contrast, species with long leaf life-span often support foliage with low SLA, N{sub mass}, and A{sub mass}, and often grow in low-temperature limited, dry, and/or nutrient-poor environments. The contrast between evergreen and deciduous species, and the implications that emerge from such comparisons, can be considered a paradigm of modern ecological theory. However, based on the results of Reich et al. (1992) and Gower et al. (1993), coniferous species with foliage that persists for 9-10 years are likely to assimilate and allocate carbon and nutrients differently than other evergreen conifers that retain foliage for 2-3 years. Thus, attempts to contrast ecophysiological or ecosystem characteristics of evergreen versus deciduous life forms may be misleading, and pronounced differences among evergreen conifers may be ignored. Clearly, the deciduous-evergreen contrast, although useful in several ways, should be viewed from the broader perspective of a gradient in leaf life-span.

  18. "Life in the Universe" Final Event Video Now Available

    NASA Astrophysics Data System (ADS)

    2002-02-01

    ESO Video Clip 01/02 is issued on the web in conjunction with the release of a 20-min documentary video from the Final Event of the "Life in the Universe" programme. This unique event took place in November 2001 at CERN in Geneva, as part of the 2001 European Science and Technology Week, an initiative by the European Commission to raise the public awareness of science in Europe. The "Life in the Universe" programme comprised competitions in 23 European countries to identify the best projects from school students. The projects could be scientific or a piece of art, a theatrical performance, poetry or even a musical performance. The only restriction was that the final work must be based on scientific evidence. Winning teams from each country were invited to a "Final Event" at CERN on 8-11 November, 2001 to present their projects to a panel of International Experts during a special three-day event devoted to understanding the possibility of other life forms existing in our Universe. This Final Event also included a spectacular 90-min webcast from CERN with the highlights of the programme. The video describes the Final Event and the enthusiastic atmosphere when more than 200 young students and teachers from all over Europe met with some of the world's leading scientific experts of the field. The present video clip, with excerpts from the film, is available in four versions: two MPEG files and two streamer-versions of different sizes; the latter require RealPlayer software. Video Clip 01/02 may be freely reproduced. The 20-min video is available on request from ESO, for viewing in VHS and, for broadcasters, in Betacam-SP format. Please contact the ESO EPR Department for more details. Life in the Universe was jointly organised by the European Organisation for Nuclear Research (CERN) , the European Space Agency (ESA) and the European Southern Observatory (ESO) , in co-operation with the European Association for Astronomy Education (EAAE). Other research organisations were

  19. Space Transportation System Availability Relationships to Life Cycle Cost

    NASA Technical Reports Server (NTRS)

    Rhodes, Russel E.; Donahue, Benjamin B.; Chen, Timothy T.

    2009-01-01

    Future space transportation architectures and designs must be affordable. Consequently, their Life Cycle Cost (LCC) must be controlled. For the LCC to be controlled, it is necessary to identify all the requirements and elements of the architecture at the beginning of the concept phase. Controlling LCC requires the establishment of the major operational cost drivers. Two of these major cost drivers are reliability and maintainability, in other words, the system's availability (responsiveness). Potential reasons that may drive the inherent availability requirement are the need to control the number of unique parts and the spare parts required to support the transportation system's operation. For more typical space transportation systems used to place satellites in space, the productivity of the system will drive the launch cost. This system productivity is the resultant output of the system availability. Availability is equal to the mean uptime divided by the sum of the mean uptime plus the mean downtime. Since many operational factors cannot be projected early in the definition phase, the focus will be on inherent availability which is equal to the mean time between a failure (MTBF) divided by the MTBF plus the mean time to repair (MTTR) the system. The MTBF is a function of reliability or the expected frequency of failures. When the system experiences failures the result is added operational flow time, parts consumption, and increased labor with an impact to responsiveness resulting in increased LCC. The other function of availability is the MTTR, or maintainability. In other words, how accessible is the failed hardware that requires replacement and what operational functions are required before and after change-out to make the system operable. This paper will describe how the MTTR can be equated to additional labor, additional operational flow time, and additional structural access capability, all of which drive up the LCC. A methodology will be presented that

  20. A novel life cycle arising from leaf segments in plants regenerated from horseradish hairy roots.

    PubMed

    Mano, Y; Matsuhashi, M

    1995-03-01

    Horseradish (Armoracia rusticana) hairy root clones were established from hairy roots which were transformed with the Ri plasmid in Agrobacterium rhizogenes 15834. The transformed plants, which were regenerated from hairy root clones, had thicker roots with extensive lateral branches and thicker stems, and grew faster compared with non-transformed horseradish plants. Small sections of leaves of the transformed plants generated adventitious roots in phytohormone-free G (modified Gamborg's) medium. Root proliferation was followed by adventitious shoot formation and plant regeneration. Approximately twenty plants were regenerated per square centimeter of leaf. The transformed plants were easily transferable from sterile conditions to soil. When leaf segments of the transformed plants were cultured in a liquid fertilizer under non-sterile conditions, adventitious roots were generated at the cut ends of the leaves. Adventitious shoots were generated at the boundary between the leaf and the adventitious roots and developed into complete plants. This novel life cycle arising from leaf segments is a unique property of the transformed plants derived from hairy root clones.

  1. Short-term effect of nutrient availability and rainfall distribution on biomass production and leaf nutrient content of savanna tree species.

    PubMed

    Barbosa, Eduardo R M; Tomlinson, Kyle W; Carvalheiro, Luísa G; Kirkman, Kevin; de Bie, Steven; Prins, Herbert H T; van Langevelde, Frank

    2014-01-01

    Changes in land use may lead to increased soil nutrient levels in many ecosystems (e.g. due to intensification of agricultural fertilizer use). Plant species differ widely in their response to differences in soil nutrients, and for savannas it is uncertain how this nutrient enrichment will affect plant community dynamics. We set up a large controlled short-term experiment in a semi-arid savanna to test how water supply (even water supply vs. natural rainfall) and nutrient availability (no fertilisation vs. fertilisation) affects seedlings' above-ground biomass production and leaf-nutrient concentrations (N, P and K) of broad-leafed and fine-leafed tree species. Contrary to expectations, neither changes in water supply nor changes in soil nutrient level affected biomass production of the studied species. By contrast, leaf-nutrient concentration did change significantly. Under regular water supply, soil nutrient addition increased the leaf phosphorus concentration of both fine-leafed and broad-leafed species. However, under uneven water supply, leaf nitrogen and phosphorus concentration declined with soil nutrient supply, this effect being more accentuated in broad-leafed species. Leaf potassium concentration of broad-leafed species was lower when growing under constant water supply, especially when no NPK fertilizer was applied. We found that changes in environmental factors can affect leaf quality, indicating a potential interactive effect between land-use changes and environmental changes on savanna vegetation: under more uneven rainfall patterns within the growing season, leaf quality of tree seedlings for a number of species can change as a response to changes in nutrient levels, even if overall plant biomass does not change. Such changes might affect herbivore pressure on trees and thus savanna plant community dynamics. Although longer term experiments would be essential to test such potential effects of eutrophication via changes in leaf nutrient concentration

  2. Short-Term Effect of Nutrient Availability and Rainfall Distribution on Biomass Production and Leaf Nutrient Content of Savanna Tree Species

    PubMed Central

    Barbosa, Eduardo R. M.; Tomlinson, Kyle W.; Carvalheiro, Luísa G.; Kirkman, Kevin; de Bie, Steven; Prins, Herbert H. T.; van Langevelde, Frank

    2014-01-01

    Changes in land use may lead to increased soil nutrient levels in many ecosystems (e.g. due to intensification of agricultural fertilizer use). Plant species differ widely in their response to differences in soil nutrients, and for savannas it is uncertain how this nutrient enrichment will affect plant community dynamics. We set up a large controlled short-term experiment in a semi-arid savanna to test how water supply (even water supply vs. natural rainfall) and nutrient availability (no fertilisation vs. fertilisation) affects seedlings’ above-ground biomass production and leaf-nutrient concentrations (N, P and K) of broad-leafed and fine-leafed tree species. Contrary to expectations, neither changes in water supply nor changes in soil nutrient level affected biomass production of the studied species. By contrast, leaf-nutrient concentration did change significantly. Under regular water supply, soil nutrient addition increased the leaf phosphorus concentration of both fine-leafed and broad-leafed species. However, under uneven water supply, leaf nitrogen and phosphorus concentration declined with soil nutrient supply, this effect being more accentuated in broad-leafed species. Leaf potassium concentration of broad-leafed species was lower when growing under constant water supply, especially when no NPK fertilizer was applied. We found that changes in environmental factors can affect leaf quality, indicating a potential interactive effect between land-use changes and environmental changes on savanna vegetation: under more uneven rainfall patterns within the growing season, leaf quality of tree seedlings for a number of species can change as a response to changes in nutrient levels, even if overall plant biomass does not change. Such changes might affect herbivore pressure on trees and thus savanna plant community dynamics. Although longer term experiments would be essential to test such potential effects of eutrophication via changes in leaf nutrient

  3. Biomass, Leaf Area, and Resource Availability of Kudzu Dominated Plant Communities Following Herbicide Treatment

    SciTech Connect

    L.T. Rader

    2001-10-01

    Kudzu is an exotic vine that threatens the forests of the southern U.S. Five herbicides were tested with regard to their efficacy in controlling kudzu, community recover was monitored, and interactions with planted pines were studied. The sites selected were old farm sites dominated by kudzu.These were burned following herbicide treatment. The herbicides included triclopyr, clopyralid, metsulfuron, tebuthiuron, and picloram plus 2,4-D. Pine seedlings were planted the following year. Regression equations were developed for predicting biomass and leaf area. Four distinct plant communities resulted from the treatments. The untreated check continued to be kudzu dominated. Blackberry dominated the clopyradid treatment. Metsulfron, trychlopyr and picloram treated sites resulted in herbaceous dominated communities. The tebuthiuron treatment maintained all vegetation low.

  4. Leaf and Life History Traits Predict Plant Growth in a Green Roof Ecosystem

    PubMed Central

    Lundholm, Jeremy; Heim, Amy; Tran, Stephanie; Smith, Tyler

    2014-01-01

    Green roof ecosystems are constructed to provide services such as stormwater retention and urban temperature reductions. Green roofs with shallow growing media represent stressful conditions for plant survival, thus plants that survive and grow are important for maximizing economic and ecological benefits. While field trials are essential for selecting appropriate green roof plants, we wanted to determine whether plant leaf traits could predict changes in abundance (growth) to provide a more general framework for plant selection. We quantified leaf traits and derived life-history traits (Grime’s C-S-R strategies) for 13 species used in a four-year green roof experiment involving five plant life forms. Changes in canopy density in monocultures and mixtures containing one to five life forms were determined and related to plant traits using multiple regression. We expected traits related to stress-tolerance would characterize the species that best grew in this relatively harsh setting. While all species survived to the end of the experiment, canopy species diversity in mixture treatments was usually much lower than originally planted. Most species grew slower in mixture compared to monoculture, suggesting that interspecific competition reduced canopy diversity. Species dominant in mixture treatments tended to be fast-growing ruderals and included both native and non-native species. Specific leaf area was a consistently strong predictor of final biomass and the change in abundance in both monoculture and mixture treatments. Some species in contrasting life-form groups showed compensatory dynamics, suggesting that life-form mixtures can maximize resilience of cover and biomass in the face of environmental fluctuations. This study confirms that plant traits can be used to predict growth performance in green roof ecosystems. While rapid canopy growth is desirable for green roofs, maintenance of species diversity may require engineering of conditions that favor less

  5. Leaf and life history traits predict plant growth in a green roof ecosystem.

    PubMed

    Lundholm, Jeremy; Heim, Amy; Tran, Stephanie; Smith, Tyler

    2014-01-01

    Green roof ecosystems are constructed to provide services such as stormwater retention and urban temperature reductions. Green roofs with shallow growing media represent stressful conditions for plant survival, thus plants that survive and grow are important for maximizing economic and ecological benefits. While field trials are essential for selecting appropriate green roof plants, we wanted to determine whether plant leaf traits could predict changes in abundance (growth) to provide a more general framework for plant selection. We quantified leaf traits and derived life-history traits (Grime's C-S-R strategies) for 13 species used in a four-year green roof experiment involving five plant life forms. Changes in canopy density in monocultures and mixtures containing one to five life forms were determined and related to plant traits using multiple regression. We expected traits related to stress-tolerance would characterize the species that best grew in this relatively harsh setting. While all species survived to the end of the experiment, canopy species diversity in mixture treatments was usually much lower than originally planted. Most species grew slower in mixture compared to monoculture, suggesting that interspecific competition reduced canopy diversity. Species dominant in mixture treatments tended to be fast-growing ruderals and included both native and non-native species. Specific leaf area was a consistently strong predictor of final biomass and the change in abundance in both monoculture and mixture treatments. Some species in contrasting life-form groups showed compensatory dynamics, suggesting that life-form mixtures can maximize resilience of cover and biomass in the face of environmental fluctuations. This study confirms that plant traits can be used to predict growth performance in green roof ecosystems. While rapid canopy growth is desirable for green roofs, maintenance of species diversity may require engineering of conditions that favor less

  6. Temperate rain forest species partition fine-scale gradients in light availability based on their leaf mass per area (LMA).

    PubMed

    Fajardo, Alex; Siefert, Andrew

    2016-12-01

    Ecologists are increasingly using plant functional traits to predict community assembly, but few studies have linked functional traits to species' responses to fine-scale resource gradients. In this study, it was tested whether saplings of woody species partition fine-scale gradients in light availability based on their leaf mass per area (LMA) in three temperate rain forests and one Mediterranean forest in southern Chile. LMA was measured under field conditions of all woody species contained in approx. 60 plots of 2 m(2) in each site, and light availability, computed as the gap light index (GLI), was determined. For each site, species' pairwise differences in mean LMA (Δ LMA) and abundance-weighted mean GLI (Δ light response) of 2 m(2) plots were calculated and it was tested whether they were positively related using Mantel tests, i.e. if species with different LMA values differed in their response to light availability. Additionally linear models were fitted to the relationship between plot-level mean LMA and GLI across plots for each site. A positive and significant relationship was found between species' pairwise differences in mean LMA and differences in light response across species for all temperate rain forests, but not for the Mediterranean forest. The results also indicated a significant positive interspecific link between LMA and light availability for all forests. This is in contrast to what is traditionally reported and to expectations from the leaf economics spectrum. In environments subjected to light limitation, interspecific differences in a leaf trait (LMA) can explain the fine-scale partitioning of light availability gradients by woody plant species. This niche partitioning potentially facilitates species coexistence at the within-community level. The high frequency of evergreen shade-intolerant species in these forests may explain the positive correlation between light availability and LMA. © The Author 2016. Published by Oxford University

  7. Leaf carbon contents vary with the plant life forms and biomes

    NASA Astrophysics Data System (ADS)

    Ma, S.; He, F.; Tian, D.; Fang, J.

    2016-12-01

    Leaf carbon content per dry mass (LCC) is an important plant trait and also a very key factor influencing our estimations of regional and global carbon sequestration in plants. Compared with the nitrogen and phosphorus, Carbon content of plants change slight, and most studies have accepted the value of 50%, however, the variations of LCC among different biomes and life forms remain unclear. By a meta-analysis, we collected 18,338 data of plants LCC from literatures and TRY database. Our result showed that the geometric mean for plant LCC was 46.82%, but varied greatly among plant life forms. Specifically, higher LCC appeared in trees and shrubs with average values of 47.64% and 46.32%, respectively. Herbaceous plants showed a lower LCC of 44.88%, while crops and aquatic plants both exhibited the lowest LCC values of 41.93% and 41.20%, respectively. Moreover, deciduous and evergreen trees had similar LCC, while coniferous trees showed higher LCC than broadleaved trees. Remarkably, the LCC of perennial herbs demonstrated the highest with an average of 45.11% among all the herbaceous plants. In summary, the LCC showed an increase with the following order of biomes: cropland, grassland, shrubland and forest. Our results indicated that the LCC of plants was lower that 50%, and could be a perfect factor to distinguish the plant life forms and biomes. Key words: leaf carbon content, plant traits, biome, life form.

  8. Leaf and ecosystem response to soil water availability in mountain grasslands

    PubMed Central

    Brilli, Federico; Hörtnagl, Lukas; Hammerle, Albin; Haslwanter, Alois; Hansel, Armin; Loreto, Francesco; Wohlfahrt, Georg

    2014-01-01

    Climate change is expected to affect the Alps by increasing the frequency and intensity of summer drought events with negative impacts on ecosystem water resources. The response of CO2 and H2O exchange of a mountain grassland to natural fluctuations of soil water content was evaluated during 2001-2009. In addition, the physiological performance of individual mountain forb and graminoid plant species under progressive soil water shortage was explored in a laboratory drought experiment. During the 9-year study period the natural occurrence of moderately to extremely dry periods did not lead to substantial reductions in net ecosystem CO2 exchange and evapotranspiration. Laboratory drought experiments confirmed that all the surveyed grassland plant species were insensitive to progressive soil drying until very low soil water contents (<0.01 m3 m−3) were reached after several days of drought. In field conditions, such a low threshold was never reached. Re-watering after a short-term drought event (5±1 days) resulted in a fast and complete recovery of the leaf CO2 and H2O gas exchange of the investigated plant species. We conclude that the present-day frequency and intensity of dry periods does not substantially affect the functioning of the investigated grassland ecosystem. During dry periods the observed “water spending” strategy employed by the investigated mountain grassland species is expected to provide a cooling feedback on climate warming, but may have negative consequences for down-stream water users. PMID:24465071

  9. Leaf and ecosystem response to soil water availability in mountain grasslands.

    PubMed

    Brilli, Federico; Hörtnagl, Lukas; Hammerle, Albin; Haslwanter, Alois; Hansel, Armin; Loreto, Francesco; Wohlfahrt, Georg

    2011-12-15

    Climate change is expected to affect the Alps by increasing the frequency and intensity of summer drought events with negative impacts on ecosystem water resources. The response of CO2 and H2O exchange of a mountain grassland to natural fluctuations of soil water content was evaluated during 2001-2009. In addition, the physiological performance of individual mountain forb and graminoid plant species under progressive soil water shortage was explored in a laboratory drought experiment. During the 9-year study period the natural occurrence of moderately to extremely dry periods did not lead to substantial reductions in net ecosystem CO2 exchange and evapotranspiration. Laboratory drought experiments confirmed that all the surveyed grassland plant species were insensitive to progressive soil drying until very low soil water contents (<0.01 m(3) m(-3)) were reached after several days of drought. In field conditions, such a low threshold was never reached. Re-watering after a short-term drought event (5±1 days) resulted in a fast and complete recovery of the leaf CO2 and H2O gas exchange of the investigated plant species. We conclude that the present-day frequency and intensity of dry periods does not substantially affect the functioning of the investigated grassland ecosystem. During dry periods the observed "water spending" strategy employed by the investigated mountain grassland species is expected to provide a cooling feedback on climate warming, but may have negative consequences for down-stream water users.

  10. Life form-specific variations in leaf water oxygen-18 enrichment in Amazonian vegetation.

    PubMed

    Lai, Chun-Ta; Ometto, Jean P H B; Berry, Joseph A; Martinelli, Luiz A; Domingues, Tomas F; Ehleringer, James R

    2008-08-01

    Leaf water (18)O enrichment (Delta(o)) influences the isotopic composition of both gas exchange and organic matter, with Delta(o) values responding to changes in atmospheric parameters. In order to examine possible influences of plant parameters on Delta(o) dynamics, we measured oxygen isotope ratios (delta(18)O) of leaf and stem water on plant species representing different life forms in Amazonia forest and pasture ecosystems. We conducted two field experiments: one in March (wet season) and another in September (dry season) 2004. In each experiment, leaf and stem samples were collected at 2-h intervals at night and hourly during the day for 50 h from eight species including upper-canopy forest trees, upper-canopy forest lianas, and lower-canopy forest trees, a C(4) pasture grass and a C(3) pasture shrub. Significant life form-related differences were detected in (18)O leaf water values. Initial modeling efforts to explain these observations over-predicted nighttime Delta(o) values by as much as 10 per thousand. Across all species, errors associated with measured values of the delta(18)O of atmospheric water vapor (delta(v)) appeared to be largely responsible for the over-predictions of nighttime Delta(o) observations. We could not eliminate collection or storage of water vapor samples as a possible error and therefore developed an alternative, plant-based method for estimating the daily average delta(v) value in the absence of direct (reliable) measurements. This approach differs from the common assumption that isotopic equilibrium exists between water vapor and precipitation water, by including transpiration-based contributions from local vegetation through (18)O measurements of bulk leaf water. Inclusion of both modified delta(v) and non-steady state features resulted in model predictions that more reliably predicted both the magnitude and temporal patterns observed in the data. The influence of life form-specific patterns of Delta(o) was incorporated through

  11. The Interplay between Carbon Availability and Growth in Different Zones of the Growing Maize Leaf1[OPEN

    PubMed Central

    Arrivault, Stéphanie; Lohse, Marc A.; Feil, Regina; Krohn, Nicole; Encke, Beatrice; Nunes-Nesi, Adriano; Fernie, Alisdair R.; Stitt, Mark

    2016-01-01

    Plants assimilate carbon in their photosynthetic tissues in the light. However, carbon is required during the night and in nonphotosynthetic organs. It is therefore essential that plants manage their carbon resources spatially and temporally and coordinate growth with carbon availability. In growing maize (Zea mays) leaf blades, a defined developmental gradient facilitates analyses in the cell division, elongation, and mature zones. We investigated the responses of the metabolome and transcriptome and polysome loading, as a qualitative proxy for protein synthesis, at dusk, dawn, and 6, 14, and 24 h into an extended night, and tracked whole-leaf elongation over this time course. Starch and sugars are depleted by dawn in the mature zone, but only after an extension of the night in the elongation and division zones. Sucrose (Suc) recovers partially between 14 and 24 h into the extended night in the growth zones, but not the mature zone. The global metabolome and transcriptome track these zone-specific changes in Suc. Leaf elongation and polysome loading in the growth zones also remain high at dawn, decrease between 6 and 14 h into the extended night, and then partially recover, indicating that growth processes are determined by local carbon status. The level of Suc-signaling metabolite trehalose-6-phosphate, and the trehalose-6-phosphate:Suc ratio are much higher in growth than mature zones at dusk and dawn but fall in the extended night. Candidate genes were identified by searching for transcripts that show characteristic temporal response patterns or contrasting responses to carbon starvation in growth and mature zones. PMID:27582314

  12. Stirling engine: Available tools for long-life assessment

    NASA Technical Reports Server (NTRS)

    Halford, Gary R.; Bartolotta, Paul A.

    1991-01-01

    A review is presented for the durability approaches applicable to long-time life assessment of Stirling engine hot-section components. The crucial elements are experimental techniques for generating long-time materials property data (both monotonic and cyclic flow and failure properties); analytic representations of slow strain rate material stress-strain response characteristics (monotonic and cyclic constitutive relations) at high temperatures and low stresses and strains; analytic creep-fatigue-environmental interaction life prediction methods applicable to long lifetimes at high temperatures and small stresses and strains; and experimental verification of life predictions. Long-lifetime design criteria for materials of interest are woefully lacking. Designing against failures due to creep, creep-rupture, fatigue, environmental attack, and creep-fatigue-environmental interaction will require considerable extrapolation. Viscoplastic constitutive models and time-temperature parameters will have to be calibrated for the hot-section materials of interest. Analysis combined with limited verification testing in a short-time regime will be required to build confidence in long-lifetime durability models.

  13. Nitrogen and water availability interact to affect leaf stoichiometry in a semi-arid grassland.

    PubMed

    Lü, Xiao-Tao; Kong, De-Liang; Pan, Qing-Min; Simmons, Matthew E; Han, Xing-Guo

    2012-02-01

    The effects of global change factors on the stoichiometric composition of green and senesced plant tissues are critical determinants of ecosystem feedbacks to anthropogenic-driven global change. So far, little is known about species stoichiometric responses to these changes. We conducted a manipulative field experiment with nitrogen (N; 17.5 g m(-2) year(-1)) and water addition (180 mm per growing season) in a temperate steppe of northern China that is potentially highly vulnerable to global change. A unique and important outcome of our study is that water availability modulated plant nutritional and stoichiometric responses to increased N availability. N addition significantly reduced C:N ratios and increased N:P ratios but only under ambient water conditions. Under increased water supply, N addition had no effect on C:N ratios in green and senesced leaves and N:P ratios in senesced leaves, and significantly decreased C:P ratios in both green and senesced leaves and N:P ratios in green leaves. Stoichiometric ratios varied greatly among species. Our results suggest that N and water addition and species identity can affect stoichiometric ratios of both green and senesced tissues through direct and interactive means. Our findings highlight the importance of water availability in modulating stoichiometric responses of plants to potentially increased N availability in semi-arid grasslands.

  14. Leaf hydraulic vulnerability to drought is linked to site water availability across a broad range of species and climates

    USDA-ARS?s Scientific Manuscript database

    Background and Aims: Vulnerability of the leaf hydraulic pathway to water-stress-induced dysfunction is a key component of drought tolerance in plants and may be important in defining species’ climatic range. However, the generality of the association between leaf hydraulic vulnerability and climate...

  15. Life history and assessment of grapevine phylloxera leaf galling incidence on Vitis species in Uruguay.

    PubMed

    Vidart, María Valeria; Mujica, María Valentina; Bao, Leticia; Duarte, Felicia; Bentancourt, Carlos María; Franco, Jorge; Scatoni, Iris Beatriz

    2013-12-01

    Grapevine phylloxera, Daktulosphaira vitifoliae (Fitch) (Hemiptera: Phylloxeridae) is a worldwide pest of Vitis species. It has forms that feed on leaves and roots. Root forms predominate on Vitis vinifera (L.) cultivars, while leaf forms predominate on Vitis species from its native American range. Recently, high densities of D. vitifoliae infestations in leaves of V. vinifera in Brazil, Peru, and Uruguay have been reported. The aims of this study were to determine the seasonal development of grape phylloxera, quantify infestation levels on V. vinifera leaves, and compare them with infestation levels on leaves of a rootstock of American origin. Studies were conducted in two vineyards in Uruguay from 2004-2007. Terminal shoots of 3309 C and Cabernet Sauvignon, Chardonnay, Tannat, Viognier, grafted onto resistant rootstock, were sampled weekly and leaves examined for gall presence and insect life stage. First galls were detected in early October; eggs began to appear within two weeks. Two oviposition peaks occurred by the end of December, and they coincided with bursts of shoot growth. On 3309C rootstock, oviposition peaks were more frequent than on the European cultivars. Based on thermal accumulation, D. vitifoliae could complete eight generations a year in Uruguay. Rootstock 3309C suffered the greatest damage but in some cases was similar to the European cultivars. Damage to Chardonnay, Cabernet Sauvignon and Viognier were also high. There were no galls on Tannat. The 2005-2006 season was characterized by low infestation rates caused by a prolonged drought that affected vegetative growth. There were also differences between vineyards, where the vigorous plants suffering more damage. Leaf galling phylloxera incidence and damage were mainly associated to the cultivar but plant vigor and environmental factors also contributed to increase the incidence.

  16. Canopy leaf area of a mature evergreen Eucalyptus woodland does not respond to elevated atmospheric [CO2] but tracks water availability.

    PubMed

    Duursma, Remko A; Gimeno, Teresa E; Boer, Matthias M; Crous, Kristine Y; Tjoelker, Mark G; Ellsworth, David S

    2016-04-01

    Canopy leaf area, quantified by the leaf area index (L), is a crucial driver of forest productivity, water use and energy balance. Because L responds to environmental drivers, it can represent an important feedback to climate change, but its responses to rising atmospheric [CO2] and water availability of forests have been poorly quantified. We studied canopy leaf area dynamics for 28 months in a native evergreen Eucalyptus woodland exposed to free-air CO2 enrichment (the EucFACE experiment), in a subtropical climate where water limitation is common. We hypothesized that, because of expected stimulation of productivity and water-use efficiency, L should increase with elevated [CO2]. We estimated L from diffuse canopy transmittance, and measured monthly leaf litter production. Contrary to expectation, L did not respond to elevated [CO2]. We found that L varied between 1.10 and 2.20 across the study period. The dynamics of L showed a quick increase after heavy rainfall and a steady decrease during periods of low rainfall. Leaf litter production was correlated to changes in L, both during periods of decreasing L (when no leaf growth occurred) and during periods of increasing L (active shedding of old foliage when new leaf growth occurred). Leaf lifespan, estimated from mean L and total annual litter production, was up to 2 months longer under elevated [CO2] (1.18 vs. 1.01 years; P = 0.05). Our main finding that L was not responsive to elevated CO2 is consistent with other forest FACE studies, but contrasts with the positive response of L commonly predicted by many ecosystem models. © 2015 John Wiley & Sons Ltd.

  17. Morphological and moisture availability controls of the leaf area-to-sapwood area ratio: analysis of measurements on Australian trees

    PubMed Central

    Togashi, Henrique Furstenau; Prentice, Iain Colin; Evans, Bradley John; Forrester, David Ian; Drake, Paul; Feikema, Paul; Brooksbank, Kim; Eamus, Derek; Taylor, Daniel

    2015-01-01

    The leaf area-to-sapwood area ratio (LA:SA) is a key plant trait that links photosynthesis to transpiration. The pipe model theory states that the sapwood cross-sectional area of a stem or branch at any point should scale isometrically with the area of leaves distal to that point. Optimization theory further suggests that LA:SA should decrease toward drier climates. Although acclimation of LA:SA to climate has been reported within species, much less is known about the scaling of this trait with climate among species. We compiled LA:SA measurements from 184 species of Australian evergreen angiosperm trees. The pipe model was broadly confirmed, based on measurements on branches and trunks of trees from one to 27 years old. Despite considerable scatter in LA:SA among species, quantile regression showed strong (0.2 < R1 < 0.65) positive relationships between two climatic moisture indices and the lowermost (5%) and uppermost (5–15%) quantiles of log LA:SA, suggesting that moisture availability constrains the envelope of minimum and maximum values of LA:SA typical for any given climate. Interspecific differences in plant hydraulic conductivity are probably responsible for the large scatter of values in the mid-quantile range and may be an important determinant of tree morphology. PMID:25859331

  18. Morphological and moisture availability controls of the leaf area-to-sapwood area ratio: analysis of measurements on Australian trees.

    PubMed

    Togashi, Henrique Furstenau; Prentice, Iain Colin; Evans, Bradley John; Forrester, David Ian; Drake, Paul; Feikema, Paul; Brooksbank, Kim; Eamus, Derek; Taylor, Daniel

    2015-03-01

    The leaf area-to-sapwood area ratio (LA:SA) is a key plant trait that links photosynthesis to transpiration. The pipe model theory states that the sapwood cross-sectional area of a stem or branch at any point should scale isometrically with the area of leaves distal to that point. Optimization theory further suggests that LA:SA should decrease toward drier climates. Although acclimation of LA:SA to climate has been reported within species, much less is known about the scaling of this trait with climate among species. We compiled LA:SA measurements from 184 species of Australian evergreen angiosperm trees. The pipe model was broadly confirmed, based on measurements on branches and trunks of trees from one to 27 years old. Despite considerable scatter in LA:SA among species, quantile regression showed strong (0.2 < R1 < 0.65) positive relationships between two climatic moisture indices and the lowermost (5%) and uppermost (5-15%) quantiles of log LA:SA, suggesting that moisture availability constrains the envelope of minimum and maximum values of LA:SA typical for any given climate. Interspecific differences in plant hydraulic conductivity are probably responsible for the large scatter of values in the mid-quantile range and may be an important determinant of tree morphology.

  19. Moisture availability constraints on the leaf area to sapwood area ratio: analysis of measurements on Australian evergreen angiosperm trees

    NASA Astrophysics Data System (ADS)

    Togashi, Henrique; Prentice, Colin; Evans, Bradley; Forrester, David; Drake, Paul; Feikema, Paul; Brooksbank, Kim; Eamus, Derek; Taylor, Daniel

    2014-05-01

    The leaf area to sapwood area ratio (LA:SA) is a key plant trait that links photosynthesis to transpiration. Pipe model theory states that the sapwood cross-sectional area of a stem or branch at any point should scale isometrically with the area of leaves distal to that point. Optimization theory further suggests that LA:SA should decrease towards drier climates. Although acclimation of LA:SA to climate has been reported within species, much less is known about the scaling of this trait with climate among species. We compiled LA:SA measurements from 184 species of Australian evergreen angiosperm trees. The pipe model was broadly confirmed, based on measurements on branches and trunks of trees from one to 27 years old. We found considerable scatter in LA:SA among species. However quantile regression showed strong (0.2availability constrains the envelope of minimum and maximum values of LA:SA typical for any given climate. Interspecific differences in plant hydraulic conductivity are probably responsible for the large scatter of values in the mid quantile-range, and may be an important determinant of tree morphology.

  20. Within-twig leaf distribution patterns differ among plant life-forms in a subtropical Chinese forest.

    PubMed

    Meng, Fengqun; Cao, Rui; Yang, Dongmei; Niklas, Karl J; Sun, Shucun

    2013-07-01

    Amax) had more even leaf distribution patterns than evergreen species (which had low LCP, LSP and Amax); shade-adapted evergreen species had more even leaf distribution patterns than sun-adapted evergreen species. We propose that the leaf distribution pattern (i.e., 'evenness' CV, which is an easily measured functional trait) can be used to distinguish among life-forms in communities similar to the one examined in this study.

  1. Effect of water availability on leaf water isotopic enrichment in beech seedlings shows limitations of current fractionation models.

    PubMed

    Ferrio, Juan Pedro; Cuntz, Matthias; Offermann, Christine; Siegwolf, Rolf; Saurer, Matthias; Gessler, Arthur

    2009-10-01

    Current models of leaf water enrichment predict that the differences between isotopic enrichment of water at the site of evaporation (Delta(e)) and mean lamina leaf water enrichment (Delta(L)) depend on transpiration rates (E), modulated by the scaled effective length (L) of water isotope movement in the leaf. However, variations in leaf parameters in response to changing environmental conditions might cause changes in the water path and thus L. We measured the diel course of Delta(L) for (18)O and (2)H in beech seedlings under well-watered and water-limited conditions. We applied evaporative enrichment models of increasing complexity to predict Delta(e) and Delta(L), and estimated L from model fits. Water-limited plants showed moderate drought stress, with lower stomatal conductance, E and stem water potential than the control. Despite having double E, the divergence between Delta(e) and Delta(L) was lower in well-watered than in water-limited plants, and thus, L should have changed to counteract differences in E. Indeed, L was about threefold higher in water-limited plants, regardless of the models used. We conclude that L changes with plant water status far beyond the variations explained by water content and other measured variables, thus limiting the use of current evaporative models under changing environmental conditions.

  2. Phenotypic plasticity and local adaptation in leaf ecophysiological traits of 13 contrasting cork oak populations under different water availabilities.

    PubMed

    Ramírez-Valiente, Jose Alberto; Sánchez-Gómez, David; Aranda, Ismael; Valladares, Fernando

    2010-05-01

    Plants distributed across a wide range of environmental conditions are submitted to differential selective pressures. Long-term selection can lead to the development of adaptations to the local environment, generating ecotypic differentiation. Additionally, plant species can cope with this environmental variability by phenotypic plasticity. In this study, we examine the importance of both processes in coping with environmental heterogeneity in the Mediterranean sclerophyllous cork oak Quercus suber. For this purpose, we measured growth and key functional traits at the leaf level in 9-year-old plants across 2 years of contrasting precipitation (2005 and 2006) in a common garden. Plants were grown from acorns originated from 13 populations spanning a wide range of climates along the distribution range of the species. The traits measured were: leaf size (LS), specific leaf area (SLA), carbon isotope discrimination (Delta(13)C) and leaf nitrogen content per unit mass (N(mass)). Inter-population differences in LS, SLA and Delta(13)C were found. These differences were associated with rainfall and temperature at the sites of origin, suggesting local adaptation in response to diverging climates. Additionally, SLA and LS exhibited positive responses to the increase in annual rainfall. Year effect explained 28% of the total phenotypic variance in LS and 2.7% in SLA. There was a significant genotype x environment interaction for shoot growth and a phenotypic correlation between the difference in shoot growth among years and the annual mean temperature at origin. This suggests that populations originating from warm sites can benefit more from wet conditions than populations from cool sites. Finally, we investigated the relationships between functional traits and aboveground growth by several regression models. Our results showed that plants with lower SLA presented larger aboveground growth in a dry year and plants with larger leaf sizes displayed larger growth rates in both

  3. Effects of atmospheric CO2 concentration, irradiance, and soil nitrogen availability on leaf photosynthetic traits of Polygonum sachalinense around natural CO2 springs in northern Japan.

    PubMed

    Osada, Noriyuki; Onoda, Yusuke; Hikosaka, Kouki

    2010-09-01

    Long-term exposure to elevated CO2 concentration will affect the traits of wild plants in association with other environmental factors. We investigated multiple effects of atmospheric CO2 concentration, irradiance, and soil N availability on the leaf photosynthetic traits of a herbaceous species, Polygonum sachalinense, growing around natural CO2 springs in northern Japan. Atmospheric CO2 concentration and its interaction with irradiance and soil N availability affected several leaf traits. Leaf mass per unit area increased and N per mass decreased with increasing CO2 and irradiance. Leaf N per area increased with increasing soil N availability at higher CO2 concentrations. The photosynthetic rate under growth CO2 conditions increased with increasing irradiance and CO2, and with increasing soil N at higher CO2 concentrations. The maximal velocity of ribulose 1,5-bisphosphate carboxylation (V (cmax)) was affected by the interaction of CO2 and soil N, suggesting that down-regulation of photosynthesis at elevated CO2 was more evident at lower soil N availability. The ratio of the maximum rate of electron transport to V (cmax) (J (max)/V (cmax)) increased with increasing CO2, suggesting that the plants used N efficiently for photosynthesis at high CO2 concentrations by changes in N partitioning. To what extent elevated CO2 influenced plant traits depended on other environmental factors. As wild plants are subject to a wide range of light and nutrient availability, our results highlight the importance of these environmental factors when the effects of elevated CO2 on plants are evaluated.

  4. Leaf physiology and biomass allocation of backcross hybrid American chestnut (Castanea dentata) seedlings in response to light and water availability.

    PubMed

    Brown, Caleb E; Mickelbart, Michael V; Jacobs, Douglass F

    2014-12-01

    Partial canopy cover promotes regeneration of many temperate forest trees, but the consequences of shading on seedling drought resistance are unclear. Reintroduction of blight-resistant American chestnut (Castanea dentata (Marsh.) Borkh.) into eastern North American forests will often occur on water-limited sites and under partial canopy cover. We measured leaf pre-dawn water potential (Ψpd), leaf gas exchange, and growth and biomass allocation of backcross hybrid American chestnut seedlings from three orchard sources grown under different light intensities (76, 26 and 8% full photosynthetically active radiation (PAR)) and subjected to well-watered or mid-season water-stressed conditions. Seedlings in the water-stress treatment were returned to well-watered conditions after wilting to examine recovery. Seedlings growing under medium- and high-light conditions wilted at lower leaf Ψpd than low-light seedlings. Recovery of net photosynthesis (Anet) and stomatal conductance (gs) was greater in low and medium light than in high light. Seed source did not affect the response to water stress or light level in most cases. Between 26 and 8% full PAR, light became limiting to the extent that the effects of water stress had no impact on some growth and morphological traits. We conclude that positive and negative aspects of shading on seedling drought tolerance and recovery are not mutually exclusive. Partial shade may help American chestnut tolerate drought during early establishment through effects on physiological conditioning. © The Author 2014. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  5. Foraging activity of an Amazonian leaf-cutting ant: responses to changes in the availability of woody plants and to previous plant damage.

    PubMed

    Vasconcelos, H L

    1997-10-01

    This study investigates some factors affecting the foraging activity of the leaf-cutting ant Atta laevigata. The study was conducted on an abandoned farm near Manaus, in Brazilian Amazonia, where forest was beginning to regenerate. I determined how temporal changes in the structure of the woody plant community (linked to the regeneration process) affected the leaf harvesting activity of this Neotropical ant. A 0.39-ha plot was established, and woody plants existing and emerging in this plot were identified, tagged, measured and mapped. At intervals of approximately 14 days all marked plants were checked to determine which had been attacked by A. laevigata during that period. Woody plant density doubled over the 18-months of the study. However, the number of plants attacked by A. laevigata, controlling for seasonal differences in ant activity, was independent of the number available for attack. The number of plants attacked was also independent of the number of new plants emerged in the previous 2 months. Apart from changes in total plant density, the relative abundance of most species also changed with time. Data on the composition of the plant community and on the composition of the ants' diet at different time intervals were subject to ordination analysis. The analyses revealed that successional changes in the composition of the woody plant community did significantly affect the composition of the leaf diet of A. laevigata. Variations in the ants' diet correlated most strongly with variations in the abundance of Bellucia imperialis. As this increased in abundance its relative contribution to the ants' diet increased. In addition, I observed a small decline in the diversity of plant resources exploited by the ants. B. imperialis was one of the species most preferred by A. laevigata, suggesting that variations in the diversity of its diet were related to the abundance of preferred species. The chances of an individual plant being attacked was independent of

  6. Nitrogen and phosphorus availabilities interact to modulate leaf trait scaling relationships across six plant functional types in a controlled-environment study.

    PubMed

    Crous, Kristine Y; O'Sullivan, Odhran S; Zaragoza-Castells, Joana; Bloomfield, Keith J; Negrini, A Clarissa A; Meir, Patrick; Turnbull, Matthew H; Griffin, Kevin L; Atkin, Owen K

    2017-08-01

    Nitrogen (N) and phosphorus (P) have key roles in leaf metabolism, resulting in a strong coupling of chemical composition traits to metabolic rates in field-based studies. However, in such studies, it is difficult to disentangle the effects of nutrient supply per se on trait-trait relationships. Our study assessed how high and low N (5 mM and 0.4 mM, respectively) and P (1 mM and 2 μM, respectively) supply in 37 species from six plant functional types (PTFs) affected photosynthesis (A) and respiration (R) (in darkness and light) in a controlled environment. Low P supply increased scaling exponents (slopes) of area-based log-log A-N or R-N relationships when N supply was not limiting, whereas there was no P effect under low N supply. By contrast, scaling exponents of A-P and R-P relationships were altered by P and N supply. Neither R : A nor light inhibition of leaf R was affected by nutrient supply. Light inhibition was 26% across nutrient treatments; herbaceous species exhibited a lower degree of light inhibition than woody species. Because N and P supply modulates leaf trait-trait relationships, the next generation of terrestrial biosphere models may need to consider how limitations in N and P availability affect trait-trait relationships when predicting carbon exchange. © 2017 The Authors. New Phytologist © 2017 New Phytologist Trust.

  7. Carbon dynamics in aboveground biomass of co-dominant plant species: related rather to leaf life span than to species

    NASA Astrophysics Data System (ADS)

    Ostler, Ulrike; Schleip, Inga; Lattanzi, Fernando A.; Schnyder, Hans

    2016-04-01

    This study investigates the role of individual organisms in whole ecosystem carbon (C) fluxes. It is currently unknown if different plant community members share the same or different kinetics of C pools in aboveground biomass, thereby adding (or not) variability to the first steps in ecosystem C cycling. We assessed the residence times in metabolic and non-metabolic (or structural) C pools and the allocation pattern of assimilated C in aboveground plant parts of four co-existing, co-dominant species from different functional groups in a temperate grassland community. For this purpose continuous, 14-16 day long 13CO2/12CO2-labeling experiments were performed in Sept. 2006, May 2007 and Sept. 2007, and the tracer kinetics were analysed with compartmental modeling. In all experimental periods, the species shared vastly similar residence times in metabolic C (5-8 d). In contrast, the residence times in non-metabolic C ranged from 20 to 58 d (except one outlier) and the fraction of fixed C allocated to the non-metabolic pool from 7 to 45%. These variations in non-metabolic C kinetics were not systematically associated with species or experimental periods, but exhibited close relationships with (independent estimates of) leaf life span, particularly in the grasses. This adds new meaning to leaf life span as a functional trait in the leaf and plant economics spectrum and its implication for C cycle studies in grassland and also forest systems. As the four co-dominant species accounted for ~80% of total community shoot biomass, we should also expect that the observed similarities in pool kinetics and allocation will scale up to similar relationships at the community level.

  8. Trade-offs between seed and leaf size (seed-phytomer-leaf theory): functional glue linking regenerative with life history strategies … and taxonomy with ecology?

    PubMed

    Hodgson, John G; Santini, Bianca A; Montserrat Marti, Gabriel; Royo Pla, Ferran; Jones, Glynis; Bogaard, Amy; Charles, Mike; Font, Xavier; Ater, Mohammed; Taleb, Abdelkader; Poschlod, Peter; Hmimsa, Younes; Palmer, Carol; Wilson, Peter J; Band, Stuart R; Styring, Amy; Diffey, Charlotte; Green, Laura; Nitsch, Erika; Stroud, Elizabeth; Romo-Díez, Angel; de Torres Espuny, Lluis; Warham, Gemma

    2017-07-27

    While the 'worldwide leaf economics spectrum' (Wright IJ, Reich PB, Westoby M, et al. 2004. The worldwide leaf economics spectrum. Nature : 821-827) defines mineral nutrient relationships in plants, no unifying functional consensus links size attributes. Here, the focus is upon leaf size, a much-studied plant trait that scales positively with habitat quality and components of plant size. The objective is to show that this wide range of relationships is explicable in terms of a seed-phytomer-leaf (SPL) theoretical model defining leaf size in terms of trade-offs involving the size, growth rate and number of the building blocks (phytomers) of which the young shoot is constructed. Functional data for 2400+ species and English and Spanish vegetation surveys were used to explore interrelationships between leaf area, leaf width, canopy height, seed mass and leaf dry matter content (LDMC). Leaf area was a consistent function of canopy height, LDMC and seed mass. Additionally, size traits are partially uncoupled. First, broad laminas help confer competitive exclusion while morphologically large leaves can, through dissection, be functionally small. Secondly, leaf size scales positively with plant size but many of the largest-leaved species are of medium height with basally supported leaves. Thirdly, photosynthetic stems may represent a functionally viable alternative to 'small seeds + large leaves' in disturbed, fertile habitats and 'large seeds + small leaves' in infertile ones. Although key elements defining the juvenile growth phase remain unmeasured, our results broadly support SPL theory in that phytometer and leaf size are a product of the size of the initial shoot meristem (≅ seed mass) and the duration and quality of juvenile growth. These allometrically constrained traits combine to confer ecological specialization on individual species. Equally, they appear conservatively expressed within major taxa. Thus, 'evolutionary canalization' sensu Stebbins (Stebbins GL

  9. Leaf ultraviolet optical properties along a latitudinal gradient in the Arctic-Alpine life zone

    SciTech Connect

    Robberecht, R.; Caldwell, M.M.; Billings, W.D.

    1980-06-01

    Leaf epidermal transmittance of terrestrial solar ultraviolet-B radiation (295 to 320 nm) was examined along a latitudinal gradient of solar uv-B radiation. In high uv-B radiation zones, e.g., equatorial and tropical regions, mean epidermal transmittance for the species examined was less than 2%. At higher latitudes, mean epidermal transmittance exceeded 5%. Although this latitudinal solar uv-B gradient represents more than a seven-fold difference in daily integrated uv-B irradiance, the calculated mean effective uv-B irradiance at the mesophyll of low-latitude species is not substantially different from that of species at higher latitudes. Species in high uv-B radiation environments appear to attenuate this radiation more effectively than those in lower irradiance environments. In most cases, absorption of uv-B in the epidermis is the major parameter effecting low transmittance. Reflectance from glabrous leaves is generally less than 10%. In some species, pubescent or glaucous leaf surfaces can reflect more than 40% of the uv-B radiation incident on a horizontal leaf, although such surface characteristics do not necessarily indicate high uv-B reflectance. Under controlled conditions, epidermal transmittance in Pisum sativum L. decreased in response to uv-B irradiation. The modification of epidermal transmittance, resulting in lower uv-B irradiance at the mesophyll, may represent a mechanism of plant acclimation to uv-B radiation. Such acclimation may have occurred in several wildland species of temperate-latitude origin that have invaded high uv-B irradiance equatorial and tropical regions.

  10. The Role of Bundle Sheath Extensions and Life Form in Stomatal Responses to Leaf Water Status1[W][OA

    PubMed Central

    Buckley, Thomas N.; Sack, Lawren; Gilbert, Matthew E.

    2011-01-01

    Bundle sheath extensions (BSEs) are key features of leaf structure with currently little-understood functions. To test the hypothesis that BSEs reduce the hydraulic resistance from the bundle sheath to the epidermis (rbe) and thereby accelerate hydropassive stomatal movements, we compared stomatal responses with reduced humidity and leaf excision among 20 species with heterobaric or homobaric leaves and herbaceous or woody life forms. We hypothesized that low rbe due to the presence of BSEs would increase the rate of stomatal opening (V) during transient wrong-way responses, but more so during wrong-way responses to excision (Ve) than humidity (Vh), thus increasing the ratio of Ve to Vh. We predicted the same trends for herbaceous relative to woody species given greater hydraulic resistance in woody species. We found that Ve, Vh, and their ratio were 2.3 to 4.4 times greater in heterobaric than homobaric leaves and 2.0 to 3.1 times greater in herbaceous than woody species. To assess possible causes for these differences, we simulated these experiments in a dynamic compartment/resistance model, which predicted larger Ve and Ve/Vh in leaves with smaller rbe. These results support the hypothesis that BSEs reduce rbe. Comparison of our data and simulations suggested that rbe is approximately 4 to 16 times larger in homobaric than heterobaric leaves. Our study provides new evidence that variations in the distribution of hydraulic resistance within the leaf and plant are central to understanding dynamic stomatal responses to water status and their ecological correlates and that BSEs play several key roles in the functional ecology of heterobaric leaves. PMID:21459977

  11. Remobilization of leaf S compounds and senescence in response to restricted sulphate supply during the vegetative stage of oilseed rape are affected by mineral N availability.

    PubMed

    Dubousset, L; Abdallah, M; Desfeux, A S; Etienne, P; Meuriot, F; Hawkesford, M J; Gombert, J; Ségura, R; Bataillé, M-P; Rezé, S; Bonnefoy, J; Ameline, A F; Ourry, A; Le Dily, F; Avice, J C

    2009-01-01

    The impact of sulphur limitation on the remobilization of endogenous S compounds during the rosette stage of oilseed rape, and the interactions with N availability on these processes, were examined using a long-term (34)SO(4)(2-) labelling method combined with a study of leaf senescence progression (using SAG12/Cab as a molecular indicator) and gene expression of the transporters, BnSultr4;1 and BnSultr4;2, involved in vacuolar sulphate efflux. After 51 d on hydroponic culture at 0.3 mM (34)SO(4)(2-) (1 atom% excess), the labelling was stopped and plants were subject for 28 d to High S-High N (HS-HN, control), Low S-High N (LS-HN) or Low S-Low N (LS-LN) conditions. Compared with the control, LS-HN plants showed delayed leaf senescence and, whilst the shoot growth and the foliar soluble protein amounts were not affected, S, (34)S, and SO(4)(2-) amounts in the old leaves declined rapidly and were associated with the up-regulation of BnSultr4;1. In LS-LN plants, shoot growth was reduced, leaf senescence was accelerated, and the rapid S mobilization in old leaves was accompanied by decreased (34)S and SO(4)(2-), higher protein mobilization, and up-regulation of BnSultr4;2, but without any change of expression of BnSultr4;1. The data suggest that to sustain the S demand for growth under S restriction (i) vacuolar SO(4)(2-) is specifically remobilized in LS-HN conditions without any acceleration of leaf senescence, (ii) SO(4)(2-) mobilization is related to an up-regulation of BnSultr4;1 and/or BnSultr4;2 expression, and (iii) the relationship between sulphate mobilization and up-regulation of expression of BnSultr4 genes is specifically dependent on the N availability.

  12. Remobilization of leaf S compounds and senescence in response to restricted sulphate supply during the vegetative stage of oilseed rape are affected by mineral N availability

    PubMed Central

    Dubousset, L.; Abdallah, M.; Desfeux, A. S.; Etienne, P.; Meuriot, F.; Hawkesford, M. J.; Gombert, J.; Ségura, R.; Bataillé, M-P.; Rezé, S.; Bonnefoy, J.; Ameline, A. F.; Ourry, A.; Dily, F. Le; Avice, J. C.

    2009-01-01

    The impact of sulphur limitation on the remobilization of endogenous S compounds during the rosette stage of oilseed rape, and the interactions with N availability on these processes, were examined using a long-term 34SO42− labelling method combined with a study of leaf senescence progression (using SAG12/Cab as a molecular indicator) and gene expression of the transporters, BnSultr4;1 and BnSultr4;2, involved in vacuolar sulphate efflux. After 51 d on hydroponic culture at 0.3 mM 34SO42− (1 atom% excess), the labelling was stopped and plants were subject for 28 d to High S-High N (HS-HN, control), Low S-High N (LS-HN) or Low S-Low N (LS-LN) conditions. Compared with the control, LS-HN plants showed delayed leaf senescence and, whilst the shoot growth and the foliar soluble protein amounts were not affected, S, 34S, and SO42− amounts in the old leaves declined rapidly and were associated with the up-regulation of BnSultr4;1. In LS-LN plants, shoot growth was reduced, leaf senescence was accelerated, and the rapid S mobilization in old leaves was accompanied by decreased 34S and SO42−, higher protein mobilization, and up-regulation of BnSultr4;2, but without any change of expression of BnSultr4;1. The data suggest that to sustain the S demand for growth under S restriction (i) vacuolar SO42− is specifically remobilized in LS-HN conditions without any acceleration of leaf senescence, (ii) SO42− mobilization is related to an up-regulation of BnSultr4;1 and/or BnSultr4;2 expression, and (iii) the relationship between sulphate mobilization and up-regulation of expression of BnSultr4 genes is specifically dependent on the N availability. PMID:19553370

  13. Stem, root, and older leaf N:P ratios are more responsive indicators of soil nutrient availability than new foliage.

    PubMed

    Schreeg, L A; Santiago, L S; Wright, S J; Turner, B L

    2014-08-01

    Foliar nitrogen to phosphorus (N:P) ratios are widely used to indicate soil nutrient availability and limitation, but the foliar ratios of woody plants have proven more complicated to interpret than ratios from whole biomass of herbaceous species. This may be related to tissues in woody species acting as nutrient reservoirs during active growth, allowing maintenance of optimal N:P ratios in recently produced, fully expanded leaves (i.e., "new" leaves, the most commonly sampled tissue). Here we address the hypothesis that N:P ratios of newly expanded leaves are less sensitive indicators of soil nutrient availability than are other tissue types in woody plants. Seedlings of five naturally established tree species were harvested from plots receiving two years of fertilizer treatments in a lowland tropical forest in the Republic of Panama. Nutrient concentrations were determined in new leaves, old leaves, stems, and roots. For stems and roots, N:P ratios increased after N addition and decreased after P addition, and trends were consistent across all five species. Older leaves also showed strong responses to N and P addition, and trends were consistent for four of five species. In comparison, overall N:P ratio responses in new leaves were more variable across species. These results indicate that the N:P ratios of stems, roots, and older leaves are more responsive indicators of soil nutrient availability than are those of new leaves. Testing the generality of this result could improve the use of tissue nutrient ratios as indices of soil nutrient availability in woody plants.

  14. Study on the Availability of Commercial Software for the Corps’ Life Cycle Project Management (LCPM)

    DTIC Science & Technology

    1989-04-01

    CLASSIFICATION OF THIS PAGE Form Approved REPORT DOCUMENTATION PAGE OM8 No. 0704-0188 la. REPORT SECURITY CLASSiFICATION ib RESTRICTVE MARKINGS...Securrty Classification ) Study on the Availability of Commercial Software for the Corps’ Life Cycle Project Management (LCPM) 12. PERSONAL AUTHOR(S...8217 ABSTRACT SECRITY CLASSIFICATION M UNCLASSIFIEDUNLIMITED C3 SAME AS RP E D iC jSERS Unciav.ified 22a. NAME OF RESPONSBLE INDVIDUAL Z.2b TE.EPiONE (Include

  15. Improvements of task performance in daily life after acquired brain injury using commonly available everyday technology.

    PubMed

    Lindén, Anita; Lexell, Jan; Larsson Lund, Maria

    2011-01-01

    To investigate how individualised occupation-based interventions with commonly available everyday technology (ET) can compensate for perceived difficulties with daily life tasks after an aquired brain injury (ABI) and improve satisfaction with occupational performance. This intervention study was designed as a multiple case study according to Yin. Ten men and women with an ABI (traumatic or non-traumatic) participated. Data were collected through interviews, observations and field notes before and after the intervention and at follow-up (on average 11 weeks afterwards). The interventions focused on enabling each participant's prioritised goals related to task performance in daily life. All participants achieved all their goals by learning to use both new functions in their own familiar ET and new ET. The participant's perceived difficulties in occupational performance decreased and their satisfaction with occupational performance increased with the use of ET. An individualised intervention process, involving the use of own familiar ET or ET off-the-shelf, has the potential to compensate for perceived difficulties following an ABI and improve satisfaction with occupational performance in daily life.

  16. Trehalose 6-Phosphate Is Required for the Onset of Leaf Senescence Associated with High Carbon Availability1[W][OA

    PubMed Central

    Wingler, Astrid; Delatte, Thierry L.; O’Hara, Liam E.; Primavesi, Lucia F.; Jhurreea, Deveraj; Paul, Matthew J.; Schluepmann, Henriette

    2012-01-01

    Trehalose 6-phosphate (T6P) is an important regulator of plant metabolism and development. T6P content increases when carbon availability is high, and in young growing tissue, T6P inhibits the activity of Snf1-related protein kinase (SnRK1). Here, strong accumulation of T6P was found in senescing leaves of Arabidopsis (Arabidopsis thaliana), in parallel with a rise in sugar contents. To determine the role of T6P in senescence, T6P content was altered by expressing the bacterial T6P synthase gene, otsA (to increase T6P), or the T6P phosphatase gene, otsB (to decrease T6P). In otsB-expressing plants, T6P accumulated less strongly during senescence than in wild-type plants, while otsA-expressing plants contained more T6P throughout. Mature otsB-expressing plants showed a similar phenotype as described for plants overexpressing the SnRK1 gene, KIN10, including reduced anthocyanin accumulation and delayed senescence. This was confirmed by quantitative reverse transcription-polymerase chain reaction analysis of senescence-associated genes and genes involved in anthocyanin synthesis. To analyze if the senescence phenotype was due to decreased sugar sensitivity, the response to sugars was determined. In combination with low nitrogen supply, metabolizable sugars (glucose, fructose, or sucrose) induced senescence in wild-type and otsA-expressing plants but to a smaller extent in otsB-expressing plants. The sugar analog 3-O-methyl glucose, on the other hand, did not induce senescence in any of the lines. Transfer of plants to and from glucose-containing medium suggested that glucose determines senescence during late development but that the effects of T6P on senescence are established by the sugar response of young plants. PMID:22247267

  17. Optimization of controlled environments for hydroponic production of leaf lettuce for human life support in CELSS

    NASA Technical Reports Server (NTRS)

    Mitchell, C. A.; Knight, S. L.; Ford, T. L.

    1986-01-01

    A research project in the food production group of the Closed Ecological Life Support System (CELSS) program sought to define optimum conditions for photosynthetic productivity of a higher plant food crop. The effects of radiation and various atmospheric compositions were studied.

  18. Leaf Development

    PubMed Central

    Tsukaya, Hirokazu

    2002-01-01

    The shoot system is the basic unit of development of seed plants and is composed of a leaf, a stem, and a lateral bud that differentiates into a lateral shoot. The most specialized organ in angiosperms, the flower, can be considered to be part of the same shoot system since floral organs, such as the sepal, petal, stamen, and carpel, are all modified leaves. Scales, bracts, and certain kinds of needle are also derived from leaves. Thus, an understanding of leaf development is critical to an understanding of shoot development. Moreover, leaves play important roles in photosynthesis, respiration and photoperception. Thus, a full understanding of leaves is directly related to a full understanding of seed plants. The details of leaf development remain unclear. The difficulties encountered in studies of leaf development, in particular in dicotyledonous plants such as Arabidopsis thaliana (L.) Henyn., are derived from the complex process of leaf development, during which the division and elongation of cells occur at the same time and in the same region of the leaf primordium (Maksymowych, 1963; Poethig and Sussex, 1985). Thus, we cannot divide the entire process into unit processes in accordance with the tenets of classical anatomy. Genetic approaches in Arabidopsis, a model plant (Meyerowitz and Pruitt, 1985), have provided a powerful tool for studies of mechanisms of leaf development in dicotyledonous plants, and various aspects of the mechanisms that control leaf development have been revealed in recent developmental and molecular genetic studies of Arabidopsis (for reviews, see Tsukaya, 1995 and 1998; Van Lijsebettens and Clarke, 1998; Sinha, 1999; Van Volkenburgh, 1999; Tsukaya, 2000; Byrne et al., 2001; Dengler and Kang, 2001; Dengler and Tsukaya, 2001; Tsukaya, 2001). In this review, we shall examine the information that is currently available about various mechanisms of leaf development in Arabidopsis. Vascular patterning is also an important factor in the

  19. Leaf δ15N as a physiological indicator of the responsiveness of N2-fixing alfalfa plants to elevated [CO2], temperature and low water availability

    PubMed Central

    Ariz, Idoia; Cruz, Cristina; Neves, Tomé; Irigoyen, Juan J.; Garcia-Olaverri, Carmen; Nogués, Salvador; Aparicio-Tejo, Pedro M.; Aranjuelo, Iker

    2015-01-01

    The natural 15N/14N isotope composition (δ15N) of a tissue is a consequence of its N source and N physiological mechanisms in response to the environment. It could potentially be used as a tracer of N metabolism in plants under changing environmental conditions, where primary N metabolism may be complex, and losses and gains of N fluctuate over time. In order to test the utility of δ15N as an indicator of plant N status in N2-fixing plants grown under various environmental conditions, alfalfa (Medicago sativa L.) plants were subjected to distinct conditions of [CO2] (400 vs. 700 μmol mol−1), temperature (ambient vs. ambient +4°C) and water availability (fully watered vs. water deficiency—WD). As expected, increased [CO2] and temperature stimulated photosynthetic rates and plant growth, whereas these parameters were negatively affected by WD. The determination of δ15N in leaves, stems, roots, and nodules showed that leaves were the most representative organs of the plant response to increased [CO2] and WD. Depletion of heavier N isotopes in plants grown under higher [CO2] and WD conditions reflected decreased transpiration rates, but could also be related to a higher N demand in leaves, as suggested by the decreased leaf N and total soluble protein (TSP) contents detected at 700 μmol mol−1 [CO2] and WD conditions. In summary, leaf δ15N provides relevant information integrating parameters which condition plant responsiveness (e.g., photosynthesis, TSP, N demand, and water transpiration) to environmental conditions. PMID:26322051

  20. Ubiquitin Ligase ATL31 Functions in Leaf Senescence in Response to the Balance Between Atmospheric CO2 and Nitrogen Availability in Arabidopsis

    PubMed Central

    Aoyama, Shoki; Huarancca Reyes, Thais; Guglielminetti, Lorenzo; Lu, Yu; Morita, Yoshie; Sato, Takeo; Yamaguchi, Junji

    2014-01-01

    Carbon (C) and nitrogen (N) are essential elements for metabolism, and their availability, called the C/N balance, must be tightly coordinated for optimal growth in plants. Previously, we have identified the ubiquitin ligase CNI1/ATL31 as a novel C/N regulator by screening plants grown on C/N stress medium containing excess sugar and limited N. To elucidate further the effect of C/N balance on plant growth and to determine the physiological function of ATL31, we performed C/N response analysis using an atmospheric CO2 manipulation system. Under conditions of elevated CO2 and sufficient N, plant biomass and total sugar and starch dramatically increased. In contrast, elevated CO2 with limited N did not increase plant biomass but promoted leaf chlorosis, with anthocyanin accumulation and increased senescence-associated gene expression. Similar results were obtained with plants grown in medium containing excess sugar and limited N, suggesting that disruption of the C/N balance affects senescence progression. In ATL31-overexpressing plants, promotion of senescence under disrupted CO2/N conditions was repressed, whereas in the loss-of-function mutant it was enhanced. The ATL31 gene was transcriptionally up-regulated under N deficiency and in senescent leaves, and ATL31 expression was highly correlated with WRKY53 expression, a key regulator of senescence. Furthermore, transient protoplast analysis implicated the direct activation of ATL31 expression by WRKY53, which was in accordance with the results of WRKY53 overexpression experiments. Together, these results demonstrate the importance of C/N balance in leaf senescence and the involvement of ubiquitin ligase ATL31 in the process of senescence in Arabidopsis. PMID:24399238

  1. Leaf Area Index Drives Soil Water Availability and Extreme Drought-Related Mortality under Elevated CO2 in a Temperate Grassland Model System

    PubMed Central

    Manea, Anthony; Leishman, Michelle R.

    2014-01-01

    The magnitude and frequency of climatic extremes, such as drought, are predicted to increase under future climate change conditions. However, little is known about how other factors such as CO2 concentration will modify plant community responses to these extreme climatic events, even though such modifications are highly likely. We asked whether the response of grasslands to repeat extreme drought events is modified by elevated CO2, and if so, what are the underlying mechanisms? We grew grassland mesocosms consisting of 10 co-occurring grass species common to the Cumberland Plain Woodland of western Sydney under ambient and elevated CO2 and subjected them to repeated extreme drought treatments. The 10 species included a mix of C3, C4, native and exotic species. We hypothesized that a reduction in the stomatal conductance of the grasses under elevated CO2 would be offset by increases in the leaf area index thus the retention of soil water and the consequent vulnerability of the grasses to extreme drought would not differ between the CO2 treatments. Our results did not support this hypothesis: soil water content was significantly lower in the mesocosms grown under elevated CO2 and extreme drought-related mortality of the grasses was greater. The C4 and native grasses had significantly higher leaf area index under elevated CO2 levels. This offset the reduction in the stomatal conductance of the exotic grasses as well as increased rainfall interception, resulting in reduced soil water content in the elevated CO2 mesocosms. Our results suggest that projected increases in net primary productivity globally of grasslands in a high CO2 world may be limited by reduced soil water availability in the future. PMID:24632832

  2. Leaf δ(15)N as a physiological indicator of the responsiveness of N2-fixing alfalfa plants to elevated [CO2], temperature and low water availability.

    PubMed

    Ariz, Idoia; Cruz, Cristina; Neves, Tomé; Irigoyen, Juan J; Garcia-Olaverri, Carmen; Nogués, Salvador; Aparicio-Tejo, Pedro M; Aranjuelo, Iker

    2015-01-01

    The natural (15)N/(14)N isotope composition (δ(15)N) of a tissue is a consequence of its N source and N physiological mechanisms in response to the environment. It could potentially be used as a tracer of N metabolism in plants under changing environmental conditions, where primary N metabolism may be complex, and losses and gains of N fluctuate over time. In order to test the utility of δ(15)N as an indicator of plant N status in N2-fixing plants grown under various environmental conditions, alfalfa (Medicago sativa L.) plants were subjected to distinct conditions of [CO2] (400 vs. 700 μmol mol(-1)), temperature (ambient vs. ambient +4°C) and water availability (fully watered vs. water deficiency-WD). As expected, increased [CO2] and temperature stimulated photosynthetic rates and plant growth, whereas these parameters were negatively affected by WD. The determination of δ(15)N in leaves, stems, roots, and nodules showed that leaves were the most representative organs of the plant response to increased [CO2] and WD. Depletion of heavier N isotopes in plants grown under higher [CO2] and WD conditions reflected decreased transpiration rates, but could also be related to a higher N demand in leaves, as suggested by the decreased leaf N and total soluble protein (TSP) contents detected at 700 μmol mol(-1) [CO2] and WD conditions. In summary, leaf δ(15)N provides relevant information integrating parameters which condition plant responsiveness (e.g., photosynthesis, TSP, N demand, and water transpiration) to environmental conditions.

  3. Complex adjustments of photosynthetic potentials and internal diffusion conductance to current and previous light availabilities and leaf age in Mediterranean evergreen species Quercus ilex.

    PubMed

    Niinemets, Ulo; Cescatti, Alessandro; Rodeghiero, Mirco; Tosens, Tiina

    2006-06-01

    Mature non-senescent leaves of evergreen species become gradually shaded as new foliage develops and canopy expands, but the interactive effects of integrated light during leaf formation (Q(int)G), current light (Q(int)C) and leaf age on foliage photosynthetic competence are poorly understood. In Quercus ilex L., we measured the responses of leaf structural and physiological variables to Q(int)C and Q(int)G for four leaf age classes. Leaf aging resulted in increases in leaf dry mass per unit area (M(A)), and leaf dry to fresh mass ratio (D(F)) and decreases in N content per dry mass (N(M)). N content per area (N(A)) was independent of age, indicating that decreases in N(M) reflected dilution of leaf N because of accumulation of dry mass (NA = N(M) M(A)). M(A), D(F) and N(A) scaled positively with irradiance, whereas these age-specific correlations were stronger with leaf growth light than with current leaf light. Area-based maximum ribulose 1,5-bisphosphate carboxylase/oxygenase (Rubisco) carboxylase activity (V(cmax)A), capacity for photosynthetic electron transport (J(max)A) and the rate of non-photorespiratory respiration in light (R(d)A) were also positively associated with irradiance. Differently from leaf structural characteristics, for all data pooled, these relationships were stronger with current light with little differences among leaves of different age. Acclimation to current leaf light environment was achieved by light-dependent partitioning of N in rate-limiting proteins. Mass-based physiological activities decreased with increasing leaf age, reflecting dilution of leaf N and a larger fraction of non-photosynthetic N in older leaves. This resulted in age-dependent modification of leaf photosynthetic potentials versus N relationships. Internal diffusion conductance (g(m)) per unit area (g(m)A) increased curvilinearly with increasing irradiance for two youngest leaf age classes and was independent of light for older leaves. In contrast, g(m) per dry

  4. Moisture Effects on Nitrogen Availability in Municipal Biosolids from End-of-Life Municipal Lagoons.

    PubMed

    Jeke, Nicholson N; Zvomuya, Francis; Ross, Lisette

    2015-11-01

    Nitrogen (N) availability affects plant biomass yield and, hence, phytoextraction of contaminants during phytoremediation of end-of-life municipal lagoons. End-of-life lagoons are characterized by fluctuating moisture conditions, but the effects on biosolid N dynamics have not been adequately characterized. This 130-d laboratory incubation investigated effects of three moisture levels (30, 60, and 90% water-filled pore space [WFPS]) on N mineralization (N) in biosolids from a primary (PB) and a secondary (SB) municipal lagoon cell. Results showed a net increase in N with time at 60% WFPS and a net decrease at 90% WFPS in PB, while N at 30% WFPS did not change significantly. Moisture level and incubation time had no significant effect on N in SB. Nitrogen mineralization rate in PB followed three-half-order kinetics. Potentially mineralizable N (N) in PB was significantly greater at 60% WFPS (222 mg kg) than at 30% WFPS (30 mg kg), but rate constants did not differ significantly between the moisture levels. Nitrogen mineralization in SB followed first-order kinetics, with N significantly greater at 60% WFPS (68.4 mg kg) and 90% WFPS (94.1 mg kg) than at 30% WFPS (32 mg kg). Low N in SB suggests high-N-demanding plants may eventually have limited effectiveness to remediate biosolids in the secondary cell. While high N in PB would provide sufficient N to support high biomass yield, phytoextraction potential is reduced under dry and near-saturated conditions. These results have important implications on the management of moisture during phytoextraction of contaminants in end-of-life municipal lagoons. Copyright © by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Inc.

  5. Genetics, phosphorus availability, and herbivore-derived induction as sources of phenotypic variation of leaf volatile terpenes in a pine species.

    PubMed

    Sampedro, Luis; Moreira, Xoaquín; Llusia, Joan; Peñuelas, Josep; Zas, Rafael

    2010-10-01

    Oleoresin produced and stored in pine tree leaves provides direct resistance to herbivores, while leaf volatile terpenes (LVT) in the resin are also powerful airborne infochemicals. Resin concentration and profile show considerable spatial and temporal phenotypic variation within and among pine populations. LVT biochemistry is known to be under genetic control, and although LVT should be plastic to diverse abiotic and biotic environmental factors such as nutrient availability and herbivore attack, little is known about their relative contributions and interactive effects. The aim of this paper was to clarify whether reduced phosphorus availability could increase the LVT concentration and affect the expression of herbivore-derived induced defences, and how plasticity would contribute to the phenotypic variation of LVT. The constitutive and methyl-jasmonate (MeJa) induced LVT concentration and profile were analysed in 17 half-sib Pinus pinaster families growing under two levels of P-availability (complete and P-limited fertilization). Individual terpene concentrations showed large additive genetic variation, which was more pronounced in the control than in MeJa-induced pines. MeJa application did not affect the LVT concentration, but significantly modified the LVT profile by depleting the α-pinene content and reducing the sesquiterpene fraction. Low P-availability strongly reduced plant growth and foliar nutrient concentrations, but did not affect LVT concentration and profile, and did not interact with MeJa-induction. Results indicate a strong homeostasis of LVT concentration to P-availability, and minor changes in the LVT profile due to MeJa-induction. Genetic variation appears to be the main source of phenotypic variation affecting the LVT concentration in this pine species.

  6. Genetics, phosphorus availability, and herbivore-derived induction as sources of phenotypic variation of leaf volatile terpenes in a pine species

    PubMed Central

    Sampedro, Luis; Llusia, Joan; Peñuelas, Josep; Zas, Rafael

    2010-01-01

    Oleoresin produced and stored in pine tree leaves provides direct resistance to herbivores, while leaf volatile terpenes (LVT) in the resin are also powerful airborne infochemicals. Resin concentration and profile show considerable spatial and temporal phenotypic variation within and among pine populations. LVT biochemistry is known to be under genetic control, and although LVT should be plastic to diverse abiotic and biotic environmental factors such as nutrient availability and herbivore attack, little is known about their relative contributions and interactive effects. The aim of this paper was to clarify whether reduced phosphorus availability could increase the LVT concentration and affect the expression of herbivore-derived induced defences, and how plasticity would contribute to the phenotypic variation of LVT. The constitutive and methyl-jasmonate (MeJa) induced LVT concentration and profile were analysed in 17 half-sib Pinus pinaster families growing under two levels of P-availability (complete and P-limited fertilization). Individual terpene concentrations showed large additive genetic variation, which was more pronounced in the control than in MeJa-induced pines. MeJa application did not affect the LVT concentration, but significantly modified the LVT profile by depleting the α-pinene content and reducing the sesquiterpene fraction. Low P-availability strongly reduced plant growth and foliar nutrient concentrations, but did not affect LVT concentration and profile, and did not interact with MeJa-induction. Results indicate a strong homeostasis of LVT concentration to P-availability, and minor changes in the LVT profile due to MeJa-induction. Genetic variation appears to be the main source of phenotypic variation affecting the LVT concentration in this pine species. PMID:20952630

  7. Social life and sanitary risks: evolutionary and current ecological conditions determine waste management in leaf-cutting ants.

    PubMed

    Farji-Brener, Alejandro G; Elizalde, Luciana; Fernández-Marín, Hermógenes; Amador-Vargas, Sabrina

    2016-05-25

    Adequate waste management is vital for the success of social life, because waste accumulation increases sanitary risks in dense societies. We explored why different leaf-cutting ants (LCA) species locate their waste in internal nest chambers or external piles, including ecological context and accounting for phylogenetic relations. We propose that waste location depends on whether the environmental conditions enhance or reduce the risk of infection. We obtained the geographical range, habitat and refuse location of LCA from published literature, and experimentally determined whether pathogens on ant waste survived to the high soil temperatures typical of xeric habitats. The habitat of the LCA determined waste location after phylogenetic correction: species with external waste piles mainly occur in xeric environments, whereas those with internal waste chambers mainly inhabit more humid habitats. The ancestral reconstruction suggests that dumping waste externally is less derived than digging waste nest chambers. Empirical results showed that high soil surface temperatures reduce pathogen prevalence from LCA waste. We proposed that LCA living in environments unfavourable for pathogens (i.e. xeric habitats) avoid digging costs by dumping the refuse above ground. Conversely, in environments suitable for pathogens, LCA species prevent the spread of diseases by storing waste underground, presumably, a behaviour that contributed to the colonization of humid habitats. These results highlight the adaptation of organisms to the hygienic challenges of social living, and illustrate how sanitary behaviours can result from a combination of evolutionary history and current environmental conditions. © 2016 The Author(s).

  8. Social life and sanitary risks: evolutionary and current ecological conditions determine waste management in leaf-cutting ants

    PubMed Central

    Farji-Brener, Alejandro G.; Elizalde, Luciana; Amador-Vargas, Sabrina

    2016-01-01

    Adequate waste management is vital for the success of social life, because waste accumulation increases sanitary risks in dense societies. We explored why different leaf-cutting ants (LCA) species locate their waste in internal nest chambers or external piles, including ecological context and accounting for phylogenetic relations. We propose that waste location depends on whether the environmental conditions enhance or reduce the risk of infection. We obtained the geographical range, habitat and refuse location of LCA from published literature, and experimentally determined whether pathogens on ant waste survived to the high soil temperatures typical of xeric habitats. The habitat of the LCA determined waste location after phylogenetic correction: species with external waste piles mainly occur in xeric environments, whereas those with internal waste chambers mainly inhabit more humid habitats. The ancestral reconstruction suggests that dumping waste externally is less derived than digging waste nest chambers. Empirical results showed that high soil surface temperatures reduce pathogen prevalence from LCA waste. We proposed that LCA living in environments unfavourable for pathogens (i.e. xeric habitats) avoid digging costs by dumping the refuse above ground. Conversely, in environments suitable for pathogens, LCA species prevent the spread of diseases by storing waste underground, presumably, a behaviour that contributed to the colonization of humid habitats. These results highlight the adaptation of organisms to the hygienic challenges of social living, and illustrate how sanitary behaviours can result from a combination of evolutionary history and current environmental conditions. PMID:27226469

  9. Oviposition, Life Cycle, and Longevity of the Leaf-Cutting Ant Acromyrmex rugosus rugosus.

    PubMed

    Verza, Sandra S; Mussury, Rosilda M; Camargo, Roberto S; Andrade, Ana Paula P; Forti, Luiz C

    2017-08-04

    Studies related to the demography of individual members from ant colonies have received little attention, although they are the basis to understanding the population dynamics of colonies. Thus, the objective of this work was to study the queen oviposition rate and the duration of the life cycle and longevity of Acromyrmex rugosus rugosus workers. To determine the oviposition rate, queens from three colonies were individually placed in plastic containers, and the eggs laid were quantified over a 96 h period. The development of the immature forms was observed every 24 h, with which the duration of each stage of development was determined. To verify the longevity of workers, the newly emerged adults were marked and daily observations were made. According to the results, there is variation in the development time of immature forms within the colony itself and between colonies. In addition, the number of eggs deposited was also inconstant in the three colonies, ranging from 5 to 119 eggs per day, while the longevity of workers varied from 3 to 7 months. Occasionally, it was found that the workers feed on the eggs produced by the queen; besides, there was a disappearance of larvae and pupae during the research, indicating a possibility of the practice of cannibalism in this species.

  10. Late-life depression in Rural China: do village infrastructure and availability of community resources matter?

    PubMed

    Li, Lydia W; Liu, Jinyu; Zhang, Zhenmei; Xu, Hongwei

    2015-07-01

    This study aimed to examine whether physical infrastructure and availability of three types of community resources (old-age income support, healthcare facilities, and elder activity centers) in rural villages are associated with depressive symptoms among older adults in rural China. Data were from the 2011 baseline survey of the Chinese Health and Retirement Longitudinal Study (CHARLS). The sample included 3824 older adults aged 60 years or older residing in 301 rural villages across China. A score of 12 on the 10-item Center for Epidemiologic Studies Depression Scale was used as the cutoff for depressed versus not depressed. Village infrastructure was indicated by an index summing deficiency in six areas: drinking water, fuel, road, sewage, waste management, and toilet facilities. Three dichotomous variables indicated whether income support, healthcare facility, and elder activity center were available in the village. Respondents' demographic characteristics (age, gender, marital status, and living arrangements), health status (chronic conditions and physical disability), and socioeconomic status (education, support from children, health insurance, household luxury items, and housing quality) were covariates. Multilevel logistic regression was conducted. Controlling for individuals' socioeconomic status, health status, and demographic characteristics, village infrastructure deficiency was positively associated with the odds of being depressed among rural older Chinese, whereas the provision of income support and healthcare facilities in rural villages was associated with lower odds. Village infrastructure and availability of community resources matter for depressive symptoms in rural older adults. Improving infrastructure, providing old-age income support, and establishing healthcare facilities in villages could be effective strategies to prevent late-life depression in rural China. Copyright © 2014 John Wiley & Sons, Ltd.

  11. Leaf age dependent changes in within-canopy variation in leaf functional traits: a meta-analysis.

    PubMed

    Niinemets, Ülo

    2016-05-01

    Within-canopy variation in leaf structural and photosynthetic characteristics is a major means by which whole canopy photosynthesis is maximized at given total canopy nitrogen. As key acclimatory modifications, leaf nitrogen content (N A) and photosynthetic capacity (A A) per unit area increase with increasing light availability in the canopy and these increases are associated with increases in leaf dry mass per unit area (M A) and/or nitrogen content per dry mass and/or allocation. However, leaf functional characteristics change with increasing leaf age during leaf development and aging, but the importance of these alterations for within-canopy trait gradients is unknown. I conducted a meta-analysis based on 71 canopies that were sampled at different time periods or, in evergreens, included measurements for different-aged leaves to understand how within-canopy variations in leaf traits (trait plasticity) depend on leaf age. The analysis demonstrated that in evergreen woody species, M A and N A plasticity decreased with increasing leaf age, but the change in A A plasticity was less suggesting a certain re-acclimation of A A to altered light. In deciduous woody species, M A and N A gradients in flush-type species increased during leaf development and were almost invariable through the rest of the season, while in continuously leaf-forming species, the trait gradients increased constantly with increasing leaf age. In forbs, N A plasticity increased, while in grasses, N A plasticity decreased with increasing leaf age, reflecting life form differences in age-dependent changes in light availability and in nitrogen resorption for growth of generative organs. Although more work is needed to improve the coverage of age-dependent plasticity changes in some plant life forms, I argue that the age-dependent variation in trait plasticity uncovered in this study is large enough to warrant incorporation in simulations of canopy photosynthesis through the growing period.

  12. The quantitative measurement of family quality of life: a review of available instruments.

    PubMed

    Hu, X; Summers, J A; Turnbull, A; Zuna, N

    2011-12-01

    Family quality of life (FQOL) has emerged as an important outcome of service delivery for individuals with disabilities and their families. The purpose of this review was to explore the disparity of scale development approaches between families with children with disabilities and families from other populations and identify strengths to serve as a source of recommendations to improve the measurements of FQOL in the disability field. We conducted a keyword search of 25 databases. Sixteen measurement tools on FQOL, family well-being and family satisfaction currently used in the disability field, healthcare field and general family studies published in journals from 1980 to 2009 were included in the analysis. Three themes emerged from the detailed analysis and comparisons of the instruments: (1) description of the primary purpose and theoretical basis; (2) identification of the tool's respondents, domains, response formats and scoring strategies to assess family systems; and (3) summarisation of available psychometric information. As family researchers continue their mission to conceptualise and theorise about FQOL, they should also promote the refinement of FQOL measurements and consider the implications from family instruments used in the healthcare and general family fields from the following aspects: (1) domains of FQOL; (2) units of analysis; (3) response format; (4) scoring choice; and (5) psychometric evaluation. © 2011 The Authors. Journal of Intellectual Disability Research © 2011 Blackwell Publishing Ltd.

  13. Education for Family Life: A Survey of Available Programs and Their Evaluation. Occasional Paper Number 4.

    ERIC Educational Resources Information Center

    Eastman, Moira

    In reviewing the literature related to education for family life, this discussion focuses on three main areas: the need for such education, trends in the development of family life education programs, and the results of evaluations of a wide range of programs. Evidence was found concerning (1) the key role families play in their members'…

  14. Mining Available Data from the United States Environmental Protection Agency to Support Rapid Life Cycle Inventory Modeling of Chemical Manufacturing

    EPA Science Inventory

    Demands for quick and accurate life cycle assessments create a need for methods to rapidly generate reliable life cycle inventories (LCI). Data mining is a suitable tool for this purpose, especially given the large amount of available governmental data. These data are typically a...

  15. Mining Available Data from the United States Environmental Protection Agency to Support Rapid Life Cycle Inventory Modeling of Chemical Manufacturing

    EPA Science Inventory

    Demands for quick and accurate life cycle assessments create a need for methods to rapidly generate reliable life cycle inventories (LCI). Data mining is a suitable tool for this purpose, especially given the large amount of available governmental data. These data are typically a...

  16. Food availability and nest predation influence life history traits in Audouin's gull, Larus audouinii.

    PubMed

    Oro, Daniel; Pradel, Roger; Lebreton, Jean-Dominique

    1999-03-01

    The effects of food availability and nest predation on several life history traits such as adult survival, dispersal, and reproductive performance were assessed in an Audouin's gull (Larus audouinii) colony during the period 1992-1997. The amounts of fish discarded from trawlers were used as a measure of food availability, and a trawling moratorium which partially overlapped with the breeding season of the gulls was taken into account. The effects of nest predation were assessed in 1994, when a terrestrial predator entered the colony and remained for the whole breeding season preying on both eggs and chicks. Using the moratorium and the predatory event as natural experiments, several hypotheses were tested: (a) food supply would affect breeding performance but not adult survival (independently of age and sex), since gulls are long-lived and adult survival is the most sensitive demographic parameter in their population dynamics; (b) the predator would trigger breeding dispersal (although gulls are mostly philopatric, they are known to abandon their natal colony after breeding failure instigated by events such as this). If breeding dispersal occurs, the rate is expected to be higher in females than in males, and higher in new breeders than in more experienced breeding birds, as is usually recorded in colonial seabirds. Probabilities of resighting and survival were estimated separately, using capture-recapture models. As expected, changes in food availability did not affect adult survival, whereas they influenced egg volume, clutch size, and breeding success. Local adult survival was estimated to be 0.908 (SD = 0.007) for males and females, and it did not change significantly with the age of individuals (range 3-8 years). The predator significantly decreased breeding success, and caused the dispersal of a number of adults probably to breed in another colony; this rate was estimated at an average of 0.10 (SD = 0.02). As expected, inexperienced breeders

  17. Does long-term fungicide exposure affect the reproductive performance of leaf-shredders? A partial life-cycle study using Hyalella azteca.

    PubMed

    Baudy, Patrick; Zubrod, Jochen P; Konschak, Marco; Weil, Mirco; Schulz, Ralf; Bundschuh, Mirco

    2017-03-01

    Leaf-shredding amphipods play a critical role in the ecosystem function of leaf litter breakdown, a key process in many low order streams. Fungicides, however, may adversely influence shredders' behavior and the functions they provide, while there is only limited knowledge concerning effects on their reproductive performance. To assess the latter, a semi-static 56-day partial life-cycle bioassay using the model shredder Hyalella azteca (n = 30) was performed applying two environmentally relevant concentrations of a model fungicide mixture (i.e., 5 and 25 μg/L) composed of five fungicides with different modes of toxic action. Variables related to the food processing (leaf consumption and feces production), growth (body length and dry weight), energy reserves (lipid content), and reproduction (amplexus pairs, number and length of offspring) were determined to understand potential implications in the organisms' energy budget. While the fungicides did not affect leaf consumption, both fungicide treatments significantly reduced amphipods' feces production (∼20%) compared to the control. This observation suggests an increased food utilization to counteract the elevated and stress-related energy demand: although growth as well as energy reserves were unaffected, amplexus pairs were less frequently observed in both fungicide treatments (∼50-100%) suggesting a tradeoff regarding energy allocation favoring the maintenance of fundamental functions at the organism level over reproduction. As a result, the time to release of first offspring was delayed in both fungicide treatments (7 and 14 days) and the median number of offspring was significantly lower in the 25-μg/L treatment (100%), whereas offspring length remained unaffected. The results of this study thus indicate that chronic fungicide exposures can negatively impact shredders' reproductive performance. This may translate into lower abundances and thus a reduced contribution to leaf litter breakdown in

  18. The qTSN4 Effect on Flag Leaf Size, Photosynthesis and Panicle Size, Benefits to Plant Grain Production in Rice, Depending on Light Availability.

    PubMed

    Fabre, Denis; Adriani, Dewi E; Dingkuhn, Michael; Ishimaru, Tsutomu; Punzalan, Bermenito; Lafarge, Tanguy; Clément-Vidal, Anne; Luquet, Delphine

    2016-01-01

    Increasing rice yield potential is essential to secure world food supply. The quantitative trait locus qTSN4 was reported to achieve yield increases by enhancing both source and sink capacity. Three greenhouse experiments and one field experiment in the Philippines were conducted to study near-isogenic lines (NILs) in two genetic backgrounds, subjected to treatments with restricted light resources through shading (greenhouse) or population density (field and greenhouse). A consistent promotion of flag leaf width, leaf area and panicle size in terms of spikelet number was observed in the presence of qTSN4, regardless of environment. However, grain production per plant was enhanced only in one greenhouse experiment. An in-depth study demonstrated that increased flag leaf size in the presence of qTSN4 was associated with increased photosynthetic rates, along with lower SLA and greater N content per leaf weight and per area. This was emphasized under low light situation as the qTSN4-NILs did not express shade acclimation traits in contrast with the recipient varieties. The authors conclude that qTSN4 is a promising subject for further physiological studies, particularly under limited radiation. However, the QTL alone may not be a reliable source of increased yield potential because its effects at the plant and population scale are prone to genotype × environment interactions and the increased panicle size is compensated by the adaptive plasticity of other morphological traits.

  19. The qTSN4 Effect on Flag Leaf Size, Photosynthesis and Panicle Size, Benefits to Plant Grain Production in Rice, Depending on Light Availability

    PubMed Central

    Fabre, Denis; Adriani, Dewi E.; Dingkuhn, Michael; Ishimaru, Tsutomu; Punzalan, Bermenito; Lafarge, Tanguy; Clément-Vidal, Anne; Luquet, Delphine

    2016-01-01

    Increasing rice yield potential is essential to secure world food supply. The quantitative trait locus qTSN4 was reported to achieve yield increases by enhancing both source and sink capacity. Three greenhouse experiments and one field experiment in the Philippines were conducted to study near-isogenic lines (NILs) in two genetic backgrounds, subjected to treatments with restricted light resources through shading (greenhouse) or population density (field and greenhouse). A consistent promotion of flag leaf width, leaf area and panicle size in terms of spikelet number was observed in the presence of qTSN4, regardless of environment. However, grain production per plant was enhanced only in one greenhouse experiment. An in-depth study demonstrated that increased flag leaf size in the presence of qTSN4 was associated with increased photosynthetic rates, along with lower SLA and greater N content per leaf weight and per area. This was emphasized under low light situation as the qTSN4-NILs did not express shade acclimation traits in contrast with the recipient varieties. The authors conclude that qTSN4 is a promising subject for further physiological studies, particularly under limited radiation. However, the QTL alone may not be a reliable source of increased yield potential because its effects at the plant and population scale are prone to genotype × environment interactions and the increased panicle size is compensated by the adaptive plasticity of other morphological traits. PMID:27242827

  20. Pinus taeda clones and soil nutrient availability: effects of soil organic matter incorporation and fertilization on biomass partitioning and leaf physiology

    Treesearch

    Michael Tyree; John Seiler; Chris Maier; Kurt Johnsen

    2009-01-01

    The combined effects of intensive management and planting of improved seedlings have led to large increases in productivity on intensively managed pine forests in the southeastern United States. To best match clones to particular site conditions, an understanding of how specific clones respond to changes in nutrition in terms of biomass partitioning, leaf physiology...

  1. Comparative analysis of the life cycle impact assessment of available cement inventories in the EU

    SciTech Connect

    Josa, Alejandro; Byars, Ewan

    2007-05-15

    Life cycle impact assessment (LCIA) is one of basic steps in life cycle assessment methodology (LCA). This paper presents a comparative study of the LCIA of different life cycle inventories (LCI) for EU cements. The analysis unit used is the manufacture of 1 kg of cement, from 'cradle to gate'. The impact categories considered are those resulting from the manufacture of cement and include greenhouse effects, acidification, eutrophication and summer and winter smog, amongst others. The results of the study highlighted some inconsistencies in existing inventories. As for the LCIA, the main environmental interventions related to cement manufacture were classified and characterised and their effect on different impact categories analysed. Differences observed in evaluation of the impact of cement type were essentially related to their clinker content.

  2. The Quantitative Measurement of Family Quality of Life: A Review of Available Instruments

    ERIC Educational Resources Information Center

    Hu, X.; Summers, J. A.; Turnbull, A.; Zuna, N.

    2011-01-01

    Background: Family quality of life (FQOL) has emerged as an important outcome of service delivery for individuals with disabilities and their families. The purpose of this review was to explore the disparity of scale development approaches between families with children with disabilities and families from other populations and identify strengths…

  3. US Activities in Making Life Cycle Inventory Data More Available to Users

    EPA Science Inventory

    The demand for LCA studies continues to grow, although, the lack of reliable, transparent Life Cycle Inventory (LCI) data is hampering the wide-spread application of LCA. This paper will present activities related to the development and accessibility of process LCI data in the U...

  4. US Activities in Making Life Cycle Inventory Data More Available to Users

    EPA Science Inventory

    The demand for LCA studies continues to grow, although, the lack of reliable, transparent Life Cycle Inventory (LCI) data is hampering the wide-spread application of LCA. This paper will present activities related to the development and accessibility of process LCI data in the U...

  5. Stirling engine - Available tools for long-life assessment. [for space propulsion

    NASA Technical Reports Server (NTRS)

    Halford, Gary R.; Bartolotta, Paul A.

    1991-01-01

    A review is presented for the durability approaches applicable to long-time life assessment of Stirling engine hot-section components. The crucial elements are experimental techniques for generating long-time materials property data (both monotonic and cyclic flow and failure properties); analytic representations of slow strain rate material stress-strain response characteristics (monotonic and cyclic constitutive relations) at high temperatures and low stresses and strains; analytic creep-fatigue-environmental interaction life prediction methods applicable to long lifetimes at high temperatures and small stresses and strains; and experimental verification of life predictions. Long-lifetime design criteria for materials of interest are woefully lacking. Designing against failures due to creep, creep-rupture, fatigue, environmental attack, and creep-failure-environmental interaction will require considerable extrapolation. Viscoplastic constitutive models and time-temperature parameters will have to be calibrated for the hot-section materials of interest. Analysis combined with limited verification testing in a short-time regime will be required to build confidence in long-lifetime durability models.

  6. Pinus taeda clones and soil nutrient availability: effects of soil organic matter incorporation and fertilization on biomass partitioning and leaf physiology.

    PubMed

    Tyree, Michael C; Seiler, John R; Maier, Chris A; Johnsen, Kurt H

    2009-09-01

    The combined effects of intensive management and planting of improved seedlings have led to large increases in productivity on intensively managed pine forests in the southeastern United States. To best match clones to particular site conditions, an understanding of how specific clones respond to changes in nutrition in terms of biomass partitioning, leaf physiology and biochemistry will be necessary. This study measured the response of biomass partitioning, light-saturated net photosynthesis (A(Sat)) and photosynthetic capacity to a range in soil fertility and fertilization between two contrasting Pinus taeda L. clone ideotypes: a 'narrow crown' clone (NC) that allocates more resources to stem growth and a 'broad crown' clone (BC) that allocates more resources to leaf area (LA). Under field conditions, we found consistent clone by environment (i.e., varying nutrient regimes) interactions in biomass as well as leaf physiology. Nutrient limitations induced by logging residue incorporation resulted in a 25% loss in stem growth in BC, while NC showed no response. We postulated that the decrease in BC was due to the differences in canopy architecture leading to a reduced canopy CO(2) assimilation, as well as to increased belowground maintenance costs associated with fine-root production. In contrast, N and P additions resulted in a 21% greater increase in stem volume in NC relative to BC. Fertilization increased A(Sat) temporarily in both clones, but A(Sat) eventually decreased below control levels by the end of the study. Although we found a clone by fertilization interaction in leaf physiology, the greatest genotype by environment interaction was found in the LA that appeared to have a greater influence than A(Sat) on growth. This research demonstrates the potential importance of selecting appropriate clonal material and silvicultural prescription when implementing site-specific silviculture to maximize productivity in intensively managed southern pine forests.

  7. Effectiveness of two-sided UV-C treatments in inhibiting natural microflora and extending the shelf-life of minimally processed 'Red Oak Leaf' lettuce.

    PubMed

    Allende, Ana; McEvoy, James L; Luo, Yaguang; Artes, Francisco; Wang, Chien Y

    2006-05-01

    The use of UV-C radiation treatments to inhibit the microbial growth and extend the shelf-life of minimally processed 'Red Oak Leaf' lettuce was investigated. Initially, UV-C resistance of 20 bacterial strains from different genera often associated with fresh produce (Enterobacter, Erwinia, Escherichia, Leuconostoc, Pantoea, Pseudomonas, Rahnela, Salmonella, Serratia and Yersinia) were tested in vitro. Most of the bacterial strains were inhibited with the minimum dose (30 J m(-2)). Erwinia carotovora, Leuconostoc carnosum, Salmonella typhimurium, and Yersinia aldovae were the most resistant strains requiring a UV-C dose of 85 J m(-2) to completely inhibit growth. An in vivo study consisted of treating minimally processed 'Red Oak Leaf' lettuce (Lactuca sativa) with UV-C at three radiation doses (1.18, 2.37 and 7.11 kJ m(-2)) on each side of the leaves and storing the product under passive MAP conditions at 5 degrees C for up to 10 days. The gas composition inside packages varied significantly among the treatments, with CO2 concentrations positively and O2 concentrations negatively correlating with the radiation dose. All the radiation doses were effective in reducing the natural microflora of the product, although the highest doses showed the greatest microbial inhibitions. Taking into account the microbial limit set by Spanish legislation [Boletín Oficial del Estado (BOE), 2001. Normas de higiene para la elaboración, distribución y comercio de comidas preparadas, Madrid, Spain, Real Decreto 3484/2000, pp. 1435-1441], all UV-C treatments extended the shelf-life of the product. However, the 7.11 kJ m(-2) dose induced tissue softening and browning after 7 days of storage at 5 degrees C. Therefore, the use of two sided UV-C radiation, at the proper dose, is effective in reducing the natural microflora and extending the shelf-life of minimally processed 'Red Oak Leaf' lettuce.

  8. Regional scale impacts of Tamarix leaf beetles (Diorhabda carinulata) on the water availability of western U.S. rivers as determined by multi-scale remote sensing methods

    USGS Publications Warehouse

    Nagler, Pamela L.; Brown, Tim; Hultine, Kevin R.; van Riper, Charles; Bean, Daniel W.; Dennison, Philip E.; Murray, R. Scott; Glenn, Edward P.

    2012-01-01

    Tamarix leaf beetles (Diorhabda carinulata) have been widely released on western U.S. rivers to control introduced shrubs in the genus Tamarix. Part of the motivation to control Tamarix is to salvage water for human use. Information is needed on the impact of beetles on Tamarix seasonal leaf production and subsequent water use overwide areas andmultiple cycles of annual defoliation.Herewe combine ground data with high resolution phenocam imagery and moderate resolution (Landsat) and coarser resolution (MODIS) satellite imagery to test the effects of beetles on Tamarix evapotranspiration (ET) and leaf phenology at sites on six western rivers. Satellite imagery covered the period 2000 to 2010 which encompassed years before and after beetle release at each study site. Phenocam images showed that beetles reduced green leaf cover of individual canopies by about 30% during a 6-8 week period in summer, but plants produced new leaves after beetles became dormant in August, and over three years no net reduction in peak summer leaf production was noted. ETwas estimated by vegetation index methods, and both Landsat and MODIS analyses showed that beetles reduced ET markedly in the first year of defoliation, but ET recovered in subsequent years. Over all six sites, ET decreased by 14% to 15% by Landsat and MODIS estimates, respectively. However, resultswere variable among sites, ranging fromno apparent effect on ET to substantial reduction in ET. Baseline ET rates before defoliation were low, 394 mmyr-1 by Landsat and 314 mm yr-1 by MODIS estimates (20-25% of potential ET), further constraining the amount of water that could be salvaged. Beetle-Tamarix interactions are in their early stage of development on this continent and it is too soon to predict the eventual extent towhich Tamarix populationswill be reduced. The utility of remote sensing methods for monitoring defoliation was constrained by the small area covered by each phenocamimage, the low temporal resolution of

  9. Leveraging Available Data to Support Extension of Transportation Packages Service Life

    SciTech Connect

    Dunn, K.; Abramczyk, G.; Bellamy, S.; Daugherty, W.; Hackney, B.; Hoffman, E.; Skidmore, E.; Stefek, T.

    2012-06-12

    Data obtained from testing shipping package materials have been leveraged to support extending the service life of select shipping packages while in nuclear materials transportation. Increasingly, nuclear material inventories are being transferred to an interim storage location where they will reside for extended periods of time. Use of a shipping package to store nuclear materials in an interim storage location has become more attractive for a variety of reasons. Shipping packages are robust and have a qualified pedigree for their performance in normal operation and accident conditions within the approved shipment period and storing nuclear material within a shipping package results in reduced operations for the storage facility. However, the shipping package materials of construction must maintain a level of integrity as specified by the safety basis of the storage facility through the duration of the storage period, which is typically well beyond the one year transportation window. Test programs have been established to obtain aging data on materials of construction that are the most sensitive/susceptible to aging in certain shipping package designs. The collective data are being used to support extending the service life of shipping packages in both transportation and storage.

  10. Resource availability, mortality, and fertility: a path analytic approach to global life-history variation.

    PubMed

    Caudell, Mark A; Quinlan, Robert J

    2012-04-01

    Humans exhibit considerable diversity in timing and rate of reproduction. Life-history theory (LHT) suggests that ecological cues of resource richness and survival probabilities shape human phenotypes across populations. Populations experiencing high extrinsic mortality due to uncertainty in resources should exhibit faster life histories. Here we use a path analytic (PA) approach informed by LHT to model the multiple pathways between resources, mortality rates, and reproductive behavior in 191 countries. Resources that account for the most variance in population mortality rates are predicted to explain the most variance in total fertility rates. Results indicate that resources (e.g., calories, sanitation, education, and health-care expenditures) influence fertility rates in paths through communicable and noncommnunicable diseases. Paths acting through communicable disease are more strongly associated with fertility than are paths through noncommunicable diseases. These results suggest that a PA approach may help disaggregate extrinsic and intrinsic mortality factors in cross-cultural analyses. Such knowledge may be useful in developing targeted policies to decrease teenage pregnancy, total fertility rates, and thus issues associated with overpopulation.

  11. Species performance: the relationship between nutrient availability, life history traits, and stress

    USDA-ARS?s Scientific Manuscript database

    The role soil nutrient availability plays in our ability to restore invasive plant dominated systems is not as straightforward as it initially appears. The objectives of this chapter are to: 1) Examine current paradigms and assumptions about how nutrient availability influences the relative perform...

  12. Relationship between leaf litter identity, expression of cytochrome P450 genes and life history traits of Aedes aegypti and Aedes albopictus.

    PubMed

    Kim, Chang-Hyun; Muturi, Ephantus J

    2012-04-01

    The role of toxic component of leaf litter in mediating the outcome of mosquito species interactions is not well documented. To examine the effect of leaf litter toxins on mosquito performance and interspecific interactions, we reared monospecific and heterospecific cultures of Aedes aegypti L. and Aedes albopictus Skuse larvae in microcosms with one of five leaf species and measured the expression of five cytochrome P450 genes and life history traits of the two mosquito species. For both mosquito species, survival to adulthood was significantly higher in black alder, black walnut, and cypress infusion compared to sugar maple and eastern white pine infusion. In pine but not in other leaf treatments, the presence of A. albopictus had significant positive effects on A. aegypti wing length and development time to adulthood. A. albopictus from heterospecific cultures were larger than those from monospecific cultures and were smaller and took longer to develop in pine and sugar maple infusions than in the other infusions. Up regulation of CYP6Z6 and CYP9M9 in A. aegypti and A. albopictus respectively appeared to be closely associated with the deleterious effects of sugar maple infusion on mosquito performance as was the down regulation of CYP6N12 (in A. aegypti) and lack of induction of CYP6Z6 and CYP9M9 (in A. aegypti and A. albopictus respectively) in pine infusion. Results suggest that metabolic capabilities that enable the two species to tolerate natural xenobiotics are associated with a fitness cost. Published by Elsevier B.V.

  13. Sensitivity of three tree ferns during their first phase of life to the variation of solar radiation and water availability in a Mexican cloud forest.

    PubMed

    Riaño, Karolina; Briones, Oscar

    2015-09-01

    Regeneration niche differentiation promotes species coexistence and diversity; however, the ecological implications for the initial life phases of the majority of pteridophytes are unknown. We analyzed the sensitivity of gametophytes and juvenile sporophytes of the tree ferns Alsophila firma, Cyathea divergens, and Lophosoria quadripinnata to variation in light and water availability. We evaluated gametophyte desiccation tolerance using saturated salt solutions and gametophyte solar radiation tolerance by direct exposure. We also transplanted juvenile sporophytes in environments with 7% and 23% canopy openness and two watering levels. The response of photosynthetic efficiency and water content suggest that the gametophytes of the three species require high relative humidity, tolerate direct solar radiation for up to 30 min and that the response is not species-dependent. Sporophyte size and gas exchange were greater in the more open site, but decreased watering had a lesser effect on these variables in the more closed site. Relative growth rate correlated with the net assimilation rate and leaf weight ratio. Juvenile sporophytes of A. firma were more shade tolerant, while those of C. divergens and L. quadripinnata acclimatized to both environments. Specialization to humid habitats in the tree fern gametophyte restricts the species to humid forests, while differences in the plasticity of the sporophyte facilitate coexistence of the species. © 2015 Botanical Society of America.

  14. Evaluation available encapsulation materials for low-cost long-life silicon photovoltaic arrays

    NASA Technical Reports Server (NTRS)

    Carmichael, D. C.; Gaines, G. B.; Noel, G. T.; Sliemers, F. A.; Nance, G. P.; Bunk, A. R.; Brockway, M. C.

    1978-01-01

    Experimental evaluation of selected encapsulation designs and materials based on an earlier study which have potential for use in low cost, long-life photovoltaic arrays are reported. The performance of candidate materials and encapsulated cells were evaluated principally for three types of encapsulation designs based on their potentially low materials and processing costs: (1) polymeric coatings, transparent conformal coatings over the cell with a structural-support substrate; (2) polymeric film lamination, cells laminated between two films or sheets of polymeric materials; and (3) glass-covered systems, cells adhesively bonded to a glass cover (superstrate) with a polymeric pottant and a glass or other substrate material. Several other design types, including those utilizing polymer sheet and pottant materials, were also included in the investigation.

  15. Direct and socially-mediated effects of food availability late in life on life-history variation in a short-lived lizard.

    PubMed

    Mugabo, Marianne; Marquis, Olivier; Perret, Samuel; Le Galliard, Jean-François

    2011-08-01

    Food availability is a major environmental factor that can influence life history within and across generations through direct effects on individual quality and indirect effects on the intensity of intra- and intercohort competition. Here, we investigated in yearling and adult common lizards (Zootoca vivipara) the immediate and delayed life-history effects of a prolonged food deprivation in the laboratory. We generated groups of fully fed or food-deprived yearlings and adults at the end of one breeding season. These lizards were released in 16 outdoor enclosures together with yearlings and adults from the same food treatment and with food-deprived or fully fed juveniles, creating four types of experimental populations. Experimental populations were then monitored during 2 years, which revealed complex effects of food on life-history trajectories. Food availability had immediate direct effects on morphology and delayed direct effects on immunocompetence and female body condition at winter emergence. Also, male annual survival rate and female growth rate and body size were affected by an interaction between direct effects of food availability and indirect effects on asymmetric competition with juveniles. Reproductive outputs were insensitive to past food availability, suggesting that female common lizards do not solely rely on stored energy to fuel reproduction. Finally, food conditions had socially-mediated intergenerational effects on early growth and survival of offspring through their effects on the intensity of competition. This study highlights the importance of social interactions among cohorts for life-history trajectories and population dynamics in stage-structured populations.

  16. Developmental plasticity of growth and digestive efficiency in dependence of early-life food availability.

    PubMed

    Kotrschal, Alexander; Szidat, Sönke; Taborsky, Barbara

    2014-08-01

    Nutrition is a potent mediator of developmental plasticity. If food is scarce, developing organisms may invest into growth to outgrow size-dependent mortality (short-term benefit) and/or into an efficient digestion system (long-term benefit). We investigated this potential trade-off, by determining the influence of food availability on juvenile body and organ growth, and on adult digestive efficiency in the cichlid fish Simochromis pleurospilus. We reared two groups of fish at constant high or low food rations, and we switched four other groups between these two rations at an early and late juvenile period. We measured juvenile growth and organ sizes at different developmental stages and determined adult digestive efficiency. Fish kept at constant, high rations grew considerably faster than low-food fish. Nevertheless, S. pleurospilus partly buffered the negative effects of low food availability by developing heavier digestive organs, and they were therefore more efficient in digesting their food as adults. Results of fish exposed to a ration switch during either the early or late juvenile period suggest (i) that the ability to show compensatory growth after early exposure to low food availability persists during the juvenile period, (ii) that digestive efficiency is influenced by varying juvenile food availability during the late juvenile phase and (iii) that the efficiency of the adult digestive system is correlated with the growth rate during a narrow time window of juvenile period.

  17. Developmental plasticity of growth and digestive efficiency in dependence of early-life food availability

    PubMed Central

    Kotrschal, Alexander; Szidat, Sönke; Taborsky, Barbara

    2014-01-01

    Nutrition is a potent mediator of developmental plasticity. If food is scarce, developing organisms may invest into growth to outgrow size-dependent mortality (short-term benefit) and/or into an efficient digestion system (long-term benefit). We investigated this potential trade-off, by determining the influence of food availability on juvenile body and organ growth, and on adult digestive efficiency in the cichlid fish Simochromis pleurospilus. We reared two groups of fish at constant high or low food rations, and we switched four other groups between these two rations at an early and late juvenile period. We measured juvenile growth and organ sizes at different developmental stages and determined adult digestive efficiency. Fish kept at constant, high rations grew considerably faster than low-food fish. Nevertheless, S. pleurospilus partly buffered the negative effects of low food availability by developing heavier digestive organs, and they were therefore more efficient in digesting their food as adults. Results of fish exposed to a ration switch during either the early or late juvenile period suggest (i) that the ability to show compensatory growth after early exposure to low food availability persists during the juvenile period, (ii) that digestive efficiency is influenced by varying juvenile food availability during the late juvenile phase and (iii) that the efficiency of the adult digestive system is correlated with the growth rate during a narrow time window of juvenile period. PMID:25866430

  18. Hypoxia tolerance in reptiles, amphibians, and fishes: life with variable oxygen availability.

    PubMed

    Bickler, Philip E; Buck, Leslie T

    2007-01-01

    The ability of fishes, amphibians, and reptiles to survive extremes of oxygen availability derives from a core triad of adaptations: profound metabolic suppression, tolerance of ionic and pH disturbances, and mechanisms for avoiding free-radical injury during reoxygenation. For long-term anoxic survival, enhanced storage of glycogen in critical tissues is also necessary. The diversity of body morphologies and habitats and the utilization of dormancy have resulted in a broad array of adaptations to hypoxia in lower vertebrates. For example, the most anoxia-tolerant vertebrates, painted turtles and crucian carp, meet the challenge of variable oxygen in fundamentally different ways: Turtles undergo near-suspended animation, whereas carp remain active and responsive in the absence of oxygen. Although the mechanisms of survival in both of these cases include large stores of glycogen and drastically decreased metabolism, other mechanisms, such as regulation of ion channels in excitable membranes, are apparently divergent. Common themes in the regulatory adjustments to hypoxia involve control of metabolism and ion channel conductance by protein phosphorylation. Tolerance of decreased energy charge and accumulating anaerobic end products as well as enhanced antioxidant defenses and regenerative capacities are also key to hypoxia survival in lower vertebrates.

  19. Efficacy of mint (Mentha arvensis) leaf and citrus (Citrus aurantium) peel extracts as natural preservatives for shelf life extension of chill stored Indian mackerel.

    PubMed

    Viji, Pankyamma; Binsi, Puthanpurakkal Kizhakkathil; Visnuvinayagam, Sivam; Bindu, Jaganath; Ravishankar, Chandragiri Nagarajarao; Srinivasa Gopal, Teralandur Krishnaswamy

    2015-10-01

    Efficacy of mint (Mentha arvensis) leaf and citrus (Citrus aurantium) peel extracts in retarding the quality changes in Indian mackerel during chilled storage was investigated. Mint leaf extract showed higher quantity of phenolics and superior in-vitro antioxidant activities than citrus peel extract. Gutted mackerel were given a dip treatment in mint extract (0.5 %, w/v) and citrus extract (1 % w/v), packed in LDPE pouches and stored at 0-2 °C. The biochemical quality indices viz. total volatile base nitrogen (TVB-N), trimethylamine nitrogen (TMA-N), free fattyacids (FFA) were significantly (p < 0.05) lower in mint extract (ME) treated fishes compared to citrus extract (CE) treated and control fishes (C) without any treatment. Plant extract treatment significantly inhibited lipid oxidation in mackerel as indicated by peroxide value (PV) and thiobarbituric acid reactive substances (TBARS). Aerobic plate count (APC) was markedly higher in C group followed by CE group throughout the storage period. As per sensory evaluation, shelf life of Indian mackerel was determined to be 11-13 days for C group, 13-15 days for CE group and 16-17 days for ME group, during storage at 0-2 °C.

  20. Assessing the Metabolic Impact of Nitrogen Availability Using a Compartmentalized Maize Leaf Genome-Scale Model1[C][W][OPEN

    PubMed Central

    Simons, Margaret; Saha, Rajib; Amiour, Nardjis; Kumar, Akhil; Guillard, Lenaïg; Clément, Gilles; Miquel, Martine; Li, Zhenni; Mouille, Gregory; Lea, Peter J.; Hirel, Bertrand; Maranas, Costas D.

    2014-01-01

    Maize (Zea mays) is an important C4 plant due to its widespread use as a cereal and energy crop. A second-generation genome-scale metabolic model for the maize leaf was created to capture C4 carbon fixation and investigate nitrogen (N) assimilation by modeling the interactions between the bundle sheath and mesophyll cells. The model contains gene-protein-reaction relationships, elemental and charge-balanced reactions, and incorporates experimental evidence pertaining to the biomass composition, compartmentalization, and flux constraints. Condition-specific biomass descriptions were introduced that account for amino acids, fatty acids, soluble sugars, proteins, chlorophyll, lignocellulose, and nucleic acids as experimentally measured biomass constituents. Compartmentalization of the model is based on proteomic/transcriptomic data and literature evidence. With the incorporation of information from the MetaCrop and MaizeCyc databases, this updated model spans 5,824 genes, 8,525 reactions, and 9,153 metabolites, an increase of approximately 4 times the size of the earlier iRS1563 model. Transcriptomic and proteomic data have also been used to introduce regulatory constraints in the model to simulate an N-limited condition and mutants deficient in glutamine synthetase, gln1-3 and gln1-4. Model-predicted results achieved 90% accuracy when comparing the wild type grown under an N-complete condition with the wild type grown under an N-deficient condition. PMID:25248718

  1. How dietary phosphorus availability during development influences condition and life history traits of the cricket, Acheta domesticas.

    PubMed

    Visanuvimol, Laksanavadee; Bertram, Susan M

    2011-01-01

    Phosphorus is extremely limited in the environment, often being 10-20 times lower in plants than what invertebrate herbivores require. This mismatch between resource availability and resource need can profoundly influence herbivore life history traits and fitness. This study investigated how dietary phosphorus availability influenced invertebrate growth, development time, consumption, condition, and lifespan using juvenile European house crickets, Acheta domesticus L. (Orthoptera: Gryllidae). Crickets reared on high phosphorus diets ate more food, gained more weight, were in better condition at maturity, and contained more phosphorus, nitrogen, and carbon in their bodies at death than crickets reared on low phosphorus diets. There was also a trend for crickets reared on high phosphorus diets to become larger adults (interaction with weight prior to the start of the experiment). These findings can be added to the small but growing number of studies that reveal the importance of phosphorus to insect life history traits. Future research should explore the importance of dietary phosphorus availability relative to protein, lipid, and carbohydrate availability.

  2. How Dietary Phosphorus Availability during Development Influences Condition and Life History Traits of the Cricket, Acheta domesticas

    PubMed Central

    Visanuvimol, Laksanavadee; Bertram, Susan M.

    2011-01-01

    Phosphorus is extremely limited in the environment, often being 10–20 times lower in plants than what invertebrate herbivores require. This mismatch between resource availability and resource need can profoundly influence herbivore life history traits and fitness. This study investigated how dietary phosphorus availability influenced invertebrate growth, development time, consumption, condition, and lifespan using juvenile European house crickets, Acheta domesticus L. (Orthoptera: Gryllidae). Crickets reared on high phosphorus diets ate more food, gained more weight, were in better condition at maturity, and contained more phosphorus, nitrogen, and carbon in their bodies at death than crickets reared on low phosphorus diets. There was also a trend for crickets reared on high phosphorus diets to become larger adults (interaction with weight prior to the start of the experiment). These findings can be added to the small but growing number of studies that reveal the importance of phosphorus to insect life history traits. Future research should explore the importance of dietary phosphorus availability relative to protein, lipid, and carbohydrate availability. PMID:21864157

  3. Community knowledge of law at the end of life: availability and accessibility of web-based resources.

    PubMed

    White, Ben; Willmott, Lindy; Tilse, Cheryl; Wilson, Jill; Lawson, Deborah; Pearce, Angela; Dunn, Jeffrey; Aitken, Joanne F; Feeney, Rachel; Jowett, Stephanie

    2017-03-30

    Objective The aim of the present study was to identify online resources community members may access to inform themselves about their legal duties and rights in end-of-life decision making.Methods Resource mapping identified online resources that members of the public in New South Wales, Victoria and Queensland are likely to identify, and assessed the ease or difficulty in locating them. Resources were then critically analysed for accessibility of language and format using the Patient Education Materials Assessment Tool (PEMAT).Results Identified resources differed considerably based on whether search terms identified by community members or experts were used. Most resources focused on advance directives, enduring powers of attorney and substitute decision making. Relatively few provided information about legal duties (e.g. powers and responsibilities of substitute decision makers) or resolving conflict with health practitioners. Accessibility (understandability and actionability) of resource content varied.Conclusions Although numerous resources on end-of-life law are available online, community members may not be able to identify relevant resources or find resource content accessible.What is known about the topic? Research on participation by patients in decision making about their treatment has focused primarily on medical rather than legal knowledge.What does this paper add? The present study investigated which online resources community members may access to inform themselves about the law on end-of-life decision making. The resources identified were analysed for ease of location and content accessibility.What are the implications for practitioners? Authors of online resources on end-of-life decision making should consider whether their resources can be: (1) identified by search terms used by the public; (2) understood by a general audience; and (3) readily used to promote reader action.

  4. Leaf Activities.

    ERIC Educational Resources Information Center

    Mingie, Walter

    Leaf activities can provide a means of using basic concepts of outdoor education to learn in elementary level subject areas. Equipment needed includes leaves, a clipboard with paper, and a pencil. A bag of leaves may be brought into the classroom if weather conditions or time do not permit going outdoors. Each student should pick a leaf, examine…

  5. Measuring quality of life in patients with breast cancer: a systematic review of reliable and valid instruments available in Japan.

    PubMed

    Okamoto, Takahiro; Shimozuma, Kojiro; Katsumata, Noriyuki; Koike, Michiko; Hisashige, Akinori; Tanaka, Katsuhiro; Ohsumi, Shozo; Saito, Mitsue; Shikama, Naoto; Mitsumori, Michihide; Yamauchi, Chikako; Watanabe, Takanori

    2003-01-01

    Little is known about the availability and psychometric properties of instruments to measure quality of life (QOL) in clinical research on Japanese patients with breast cancer. The purpose of this systematic review is to find reliable and valid instruments available in Japan, and to summarize their characteristics. Instruments available in Japan were found through a systematic search of the literature. Each instrument identified was evaluated for item development, reliability, validity, interpretability and utility. Six questionnaires to measure health-related QOL (the QOL-ACD, the EORTC QLQ-C30, the EORTC QLQ-BR23, the FACT-B, the SF-36, the WHO/QOL-26) and five scales to quantify the psychological burden (the STAI, the POMS, the SDS, the HADS, the GHQ), for which reliability and validity have been documented, are available in Japanese. All instruments were developed in foreign countries except for the QOL-ACD. Two of the QOL questionnaires were specific to breast cancer (the EORTC QLQ-BR23, the FACT-B). Though the measurements can be interpreted in some manner, the meaning of change scores over time has been documented for only three instruments (the EORTC QLQ-C30, the FACT-B, and the GHQ). The review provides grounds for designing and implementing quantitative research on QOL of breast cancer patients in Japan. Methodological challenges, however, continue, particularly for validating instruments with regard to various study populations of Japanese people and demonstrating the clinical importance of change scores.

  6. Mining Available Data from the United States Environmental Protection Agency to Support Rapid Life Cycle Inventory Modeling of Chemical Manufacturing.

    PubMed

    Cashman, Sarah A; Meyer, David E; Edelen, Ashley N; Ingwersen, Wesley W; Abraham, John P; Barrett, William M; Gonzalez, Michael A; Randall, Paul M; Ruiz-Mercado, Gerardo; Smith, Raymond L

    2016-09-06

    Demands for quick and accurate life cycle assessments create a need for methods to rapidly generate reliable life cycle inventories (LCI). Data mining is a suitable tool for this purpose, especially given the large amount of available governmental data. These data are typically applied to LCIs on a case-by-case basis. As linked open data becomes more prevalent, it may be possible to automate LCI using data mining by establishing a reproducible approach for identifying, extracting, and processing the data. This work proposes a method for standardizing and eventually automating the discovery and use of publicly available data at the United States Environmental Protection Agency for chemical-manufacturing LCI. The method is developed using a case study of acetic acid. The data quality and gap analyses for the generated inventory found that the selected data sources can provide information with equal or better reliability and representativeness on air, water, hazardous waste, on-site energy usage, and production volumes but with key data gaps including material inputs, water usage, purchased electricity, and transportation requirements. A comparison of the generated LCI with existing data revealed that the data mining inventory is in reasonable agreement with existing data and may provide a more-comprehensive inventory of air emissions and water discharges. The case study highlighted challenges for current data management practices that must be overcome to successfully automate the method using semantic technology. Benefits of the method are that the openly available data can be compiled in a standardized and transparent approach that supports potential automation with flexibility to incorporate new data sources as needed.

  7. The genome of the leaf-cutting ant Acromyrmex echinatior suggests key adaptations to advanced social life and fungus farming

    PubMed Central

    Nygaard, Sanne; Zhang, Guojie; Schiøtt, Morten; Li, Cai; Wurm, Yannick; Hu, Haofu; Zhou, Jiajian; Ji, Lu; Qiu, Feng; Rasmussen, Morten; Pan, Hailin; Hauser, Frank; Krogh, Anders; Grimmelikhuijzen, Cornelis J.P.; Wang, Jun; Boomsma, Jacobus J.

    2011-01-01

    We present a high-quality (>100× depth) Illumina genome sequence of the leaf-cutting ant Acromyrmex echinatior, a model species for symbiosis and reproductive conflict studies. We compare this genome with three previously sequenced genomes of ants from different subfamilies and focus our analyses on aspects of the genome likely to be associated with known evolutionary changes. The first is the specialized fungal diet of A. echinatior, where we find gene loss in the ant's arginine synthesis pathway, loss of detoxification genes, and expansion of a group of peptidase proteins. One of these is a unique ant-derived contribution to the fecal fluid, which otherwise consists of “garden manuring” fungal enzymes that are unaffected by ant digestion. The second is multiple mating of queens and ejaculate competition, which may be associated with a greatly expanded nardilysin-like peptidase gene family. The third is sex determination, where we could identify only a single homolog of the feminizer gene. As other ants and the honeybee have duplications of this gene, we hypothesize that this may partly explain the frequent production of diploid male larvae in A. echinatior. The fourth is the evolution of eusociality, where we find a highly conserved ant-specific profile of neuropeptide genes that may be related to caste determination. These first analyses of the A. echinatior genome indicate that considerable genetic changes are likely to have accompanied the transition from hunter-gathering to agricultural food production 50 million years ago, and the transition from single to multiple queen mating 10 million years ago. PMID:21719571

  8. Project LEAF

    EPA Pesticide Factsheets

    Project LEAF has a goal of educating farmworkers about how to reduce pesticide exposure to their families from pesticide residues they may be inadvertently taking home on their clothing, etc. Find outreach materials.

  9. Theoretical life history responses of juvenile Oncorhynchus mykiss to changes in food availability using a dynamic state-dependent approach

    USGS Publications Warehouse

    Romine, Jason G.; Benjamin, Joseph R.; Perry, Russell W.; Casal, Lynne; Connolly, Patrick J.; Sauter, Sally S.

    2013-01-01

    Marine subsidies can play an important role in the growth, survival, and migratory behavior of rearing juvenile salmonids. Availability of high-energy, marine-derived food sources during critical decision windows may influence the timing of emigration or the decision to forego emigration completely and remain in the freshwater environment. Increasing growth and growth rate during these decision windows may result in an altered juvenile population structure, which will ultimately affect the adult population age-structure. We used a state dependent model to understand how the juvenile Oncorhynchus mykiss population structure may respond to increased availability of salmon eggs in their diet during critical decision windows. Our models predicted an increase in smolt production until coho salmon eggs comprised more than 50 percent of juvenile O. mykiss diet at the peak of the spawning run. At higher-than intermediate levels of egg consumption, smolt production decreased owing to increasing numbers of fish adopting a resident life-history strategy. Additionally, greater growth rates decreased the number of age-3 smolts and increased the number of age-2 smolts. Increased growth rates with higher egg consumption also decreased the age at which fish adopted the resident pathway. Our models suggest that the introduction of a high-energy food source during critical periods of the year could be sufficient to increase smolt production.

  10. Vitamins, stress and growth: the availability of antioxidants in early life influences the expression of cryptic genetic variation.

    PubMed

    Kim, S-Y; Noguera, J C; Tato, A; Velando, A

    2013-06-01

    Environmental inputs during early development can shape the expression of phenotypes, which has long-lasting consequences in physiology and life history of an organism. Here, we study whether experimentally manipulated availability of dietary antioxidants, vitamins C and E, influences the expression of genetic variance for antioxidant defence, endocrine signal and body mass in yellow-legged gull chicks using quantitative genetic models based on full siblings. Our experimental study in a natural population reveals that the expression of genetic variance in total antioxidant capacity in plasma increased in chicks supplemented with vitamins C and E despite the negligible effects on the average phenotype. This suggests that individuals differ in their ability to capture and transport dietary antioxidants or to respond to these extra resources, and importantly, this ability has a genetic basis. Corticosterone level in plasma and body mass were negatively correlated at the phenotypic level. Significant genetic variance of corticosterone level appeared only in control chicks nonsupplemented with vitamins, suggesting that the genetic variation of endocrine system, which transmits environmental cues to adaptively control chick development, appeared in stressful conditions (i.e. poor antioxidant availability). Therefore, environmental inputs may shape evolutionary trajectories of antioxidant capacity and endocrine system by affecting the expression of cryptic genetic variation. © 2013 The Authors. Journal of Evolutionary Biology © 2013 European Society For Evolutionary Biology.

  11. Management practices for end-of-life cathode ray tube glass: Review of advances in recycling and best available technologies.

    PubMed

    Iniaghe, Paschal O; Adie, Gilbert U

    2015-11-01

    Cathode ray tubes are image display units found in computer monitors and televisions. In recent years, cathode ray tubes have been generated as waste owing to the introduction of newer and advanced technologies in image displays, such as liquid crystal displays and high definition televisions, among others. Generation and subsequent disposal of end-of-life cathode ray tubes presents a challenge owing to increasing volumes and high lead content embedded in the funnel and neck sections of the glass. Disposal in landfills and open dumping are anti-environmental practices considering the large-scale contamination of environmental media by the potential of toxic metals leaching from glass. Mitigating such environmental contamination will require sound management strategies that are environmentally friendly and economically feasible. This review covers existing and emerging management practices for end-of-life cathode ray tubes. An in-depth analysis of available technologies (glass smelting, detoxification of cathode ray tube glass, lead extraction from cathode ray tube glass) revealed that most of the techniques are environmentally friendly, but are largely confined to either laboratory scale, or are often limited owing to high cost to mount, or generate secondary pollutants, while a closed-looped method is antiquated. However, recycling in cementitious systems (cement mortar and concrete) gives an added advantage in terms of quantity of recyclable cathode ray tube glass at a given time, with minimal environmental and economic implications. With significant quantity of waste cathode ray tube glass being generated globally, cementitious systems could be economically and environmentally acceptable as a sound management practice for cathode ray tube glass, where other technologies may not be applicable. © The Author(s) 2015.

  12. Effects of phosphorus availability and genetic variation of leaf terpene content and emission rate in Pinus pinaster seedlings susceptible and resistant to the pine weevil, Hylobius abietis.

    PubMed

    Blanch, J-S; Sampedro, L; Llusià, J; Moreira, X; Zas, R; Peñuelas, J

    2012-03-01

    We studied the effects of phosphorus fertilisation on foliar terpene concentrations and foliar volatile terpene emission rates in six half-sib families of Pinus pinaster Ait. seedlings. Half of the seedlings were resistant to attack of the pine weevil Hylobius abietis L., a generalist phloem feeder, and the remaining seedlings were susceptible to this insect. We hypothesised that P stress could modify the terpene concentration in the needles and thus lead to altered terpene emission patterns relevant to plant-insect signalling. The total concentration and emission rate ranged between 5732 and 13,995 μg·g(-1) DW and between 2 and 22 μg·g(-1) DW·h(-1), respectively. Storage and emission were dominated by the isomers α- and β-pinene (77.2% and 84.2% of the total terpene amount amassed and released, respectively). In both resistant and susceptible families, P stress caused an increase of 31% in foliar terpene concentration with an associated 5-fold decrease in terpene emission rates. A higher terpene content in the leaves implies that the 'excess carbon', available under limiting growth conditions (P scarcity), is allocated to terpene production. Sensitive families showed a greater increase in terpene emission rates with increasing P concentrations, which could explain their susceptibility to H. abietis.

  13. Warming does not stimulate mitochondrial respiration and it responds to leaf carbohydrates availability in soybean plants grown under elevated CO2 concentrations

    NASA Astrophysics Data System (ADS)

    Ruiz Vera, U. M.; Gomez-Casanovas, N.; Bernacchi, C.; Ort, D. R.; Siebers, M.

    2015-12-01

    There is a lack of understanding on the mechanism underlying the response of mitochondrial respiration (Rs) to the single and combined effects of increasing CO2 concentration ([CO2]) and warming. We investigated the response of Rs to the single and combined effects of elevated [CO2] and warming in soybean plants over a complete growing season using Temperature by Free Air CO2 enrichment technology under field conditions. The treatments were: control, elevated [CO2] (eC), high temperature (eT), and elevated [CO2]+high temperature (eT+eC). Given that photosynthetic rates in eT+eC grown plants were not higher than in plants grown under eC, we hypothesized that Rs would increase only slightly in plants grown under eT+eC compared to eC plants, due to the increase of temperature. Contrary to our prediction, our preliminary results showed that plants grown under the warming treatments had low Rs, thus eT+eC had lower Rs than eC. The response of Rs to these factors was consistent at two different plant high levels (canopy and five nodes down the canopy). Changes in Rs were explained by variations in the carbohydrate content. Our results indicate that the response of Rs to changes in [CO2] and temperature will depend on the carbohydrate availability of plant tissues and thus on how photosynthesis is affected by this environmental factors.

  14. Size-dependent leaf area ratio in plant twigs: implication for leaf size optimization

    PubMed Central

    Yang, Dongmei; Niklas, Karl J.; Xiang, Shuang; Sun, Shucun

    2010-01-01

    Background and Aims Although many hypotheses have been proposed to explain variation in leaf size, the mechanism underlying the variation remains not fully understood. To help understand leaf size variation, the cost/benefit of twig size was analysed, since, according to Corner's rule, twig size is positively correlated with the size of appendages the twig bears. Methods An extensive survey of twig functional traits, including twig (current-year shoots including one stem and few leaves) and leaf size (individual leaf area and mass), was conducted for 234 species from four broadleaved forests. The scaling relationship between twig mass and leaf area was determined using standardized major axis regression and phylogenetic independent comparative analyses. Key Results Leaf area was found to scale positively and allometrically with both stem and twig mass (stem mass plus leaf mass) with slopes significantly smaller than 1·0, independent of life form and habitat type. Thus, the leaf area ratio (the ratio of total leaf area to stem or twig mass) decreases with increasing twig size. Moreover, the leaf area ratio correlated negatively with individual leaf mass. The results of phylogenetic independent comparativeanalyses were consistent with the correlations. Based on the above results, a simple model for twig size optimization was constructed, from which it is postulated that large leaf size–twig size may be favoured when leaf photosynthetic capacity is high and/or when leaf life span and/or stem longevity are long. The model's predictions are consistent with leaf size variation among habitats, in which leaf size tends to be small in poor habitats with a low primary productivity. The model also explains large variations in leaf size within habitats for which leaf longevity and stem longevity serve as important determinants. Conclusions The diminishing returns in the scaling of total leaf area with twig size can be explained in terms of a very simple model on twig size

  15. Maximum growth rates and possible life strategies of different bacterioplankton groups in relation to phosphorus availability in a freshwater reservoir.

    PubMed

    Simek, Karel; Hornák, Karel; Jezbera, Jan; Nedoma, Jirí; Vrba, Jaroslav; Straskrábová, Viera; Macek, Miroslav; Dolan, John R; Hahn, Martin W

    2006-09-01

    We investigated net growth rates of distinct bacterioplankton groups and heterotrophic nanoflagellate (HNF) communities in relation to phosphorus availability by analysing eight in situ manipulation experiments, conducted between 1997 and 2003, in the canyon-shaped Rímov reservoir (Czech Republic). Water samples were size-fractionated and incubated in dialysis bags at the sampling site or transplanted into an area of the reservoir, which differed in phosphorus limitation (range of soluble reactive phosphorus concentrations--SRP, 0.7-96 microg l-1). Using five different rRNA-targeted oligonucleotide probes, net growth rates of the probe-defined bacterial groups and HNF assemblages were estimated and related to SRP using Monod kinetics, yielding growth rate constants specific for each bacterial group. We found highly significant differences among their maximum growth rates while insignificant differences were detected in the saturation constants. However, the latter constants represent only tentative estimates mainly due to insufficient sensitivity of the method used at low in situ SRP concentrations. Interestingly, in these same experiments HNF assemblages grew significantly faster than any bacterial group studied except for a small, but abundant cluster of Betaproteobacteria (targeted by the R-BT065 probe). Potential ecological implications of different growth capabilities for possible life strategies of different bacterial phylogenetic lineages are discussed.

  16. Leafing patterns and leaf traits of four evergreen shrubs in the Patagonian Monte, Argentina

    NASA Astrophysics Data System (ADS)

    Campanella, María Victoria; Bertiller, Mónica B.

    2009-11-01

    We assessed leafing patterns (rate, timing, and duration of leafing) and leaf traits (leaf longevity, leaf mass per area and leaf-chemistry) in four co-occurring evergreen shrubs of the genus Larrea and Chuquiraga (each having two species) in the arid Patagonian Monte of Argentina. We asked whether species with leaves well-defended against water shortage (high LMA, leaf longevity, and lignin concentration, and low N concentration) have lower leaf production, duration of the leafing period, and inter-annual variation of leafing than species with the opposite traits. We observed two distinctive leafing patterns each related to one genus. Chuquiraga species produced new leaves concentrated in a massive short leafing event (5-48 days) while new leaves of Larrea species emerged gradually (128-258 days). Observed leafing patterns were consistent with simultaneous and successive leafing types previously described for woody plants. The peak of leaf production occurred earlier in Chuquiraga species (mid September) than in Larrea species (mid October-late November). Moreover, Chuquiraga species displayed leaves with the longest leaf lifespan, while leaves of Larrea species had the lowest LMA and the highest N and soluble phenolics concentrations. We also observed that only the leaf production of Larrea species increased in humid years. We concluded that co-occurring evergreen species in the Patagonian Monte displayed different leafing patterns, which were associated with some relevant leaf traits acting as plant defenses against water stress and herbivores. Differences in leafing patterns could provide evidence of ecological differentiation among coexisting species of the same life form.

  17. Leaf Development

    PubMed Central

    2013-01-01

    Leaves are the most important organs for plants. Without leaves, plants cannot capture light energy or synthesize organic compounds via photosynthesis. Without leaves, plants would be unable perceive diverse environmental conditions, particularly those relating to light quality/quantity. Without leaves, plants would not be able to flower because all floral organs are modified leaves. Arabidopsis thaliana is a good model system for analyzing mechanisms of eudicotyledonous, simple-leaf development. The first section of this review provides a brief history of studies on development in Arabidopsis leaves. This history largely coincides with a general history of advancement in understanding of the genetic mechanisms operating during simple-leaf development in angiosperms. In the second section, I outline events in Arabidopsis leaf development, with emphasis on genetic controls. Current knowledge of six important components in these developmental events is summarized in detail, followed by concluding remarks and perspectives. PMID:23864837

  18. Leaf development: a cellular perspective

    PubMed Central

    Kalve, Shweta; De Vos, Dirk; Beemster, Gerrit T. S.

    2014-01-01

    Through its photosynthetic capacity the leaf provides the basis for growth of the whole plant. In order to improve crops for higher productivity and resistance for future climate scenarios, it is important to obtain a mechanistic understanding of leaf growth and development and the effect of genetic and environmental factors on the process. Cells are both the basic building blocks of the leaf and the regulatory units that integrate genetic and environmental information into the developmental program. Therefore, to fundamentally understand leaf development, one needs to be able to reconstruct the developmental pathway of individual cells (and their progeny) from the stem cell niche to their final position in the mature leaf. To build the basis for such understanding, we review current knowledge on the spatial and temporal regulation mechanisms operating on cells, contributing to the formation of a leaf. We focus on the molecular networks that control exit from stem cell fate, leaf initiation, polarity, cytoplasmic growth, cell division, endoreduplication, transition between division and expansion, expansion and differentiation and their regulation by intercellular signaling molecules, including plant hormones, sugars, peptides, proteins, and microRNAs. We discuss to what extent the knowledge available in the literature is suitable to be applied in systems biology approaches to model the process of leaf growth, in order to better understand and predict leaf growth starting with the model species Arabidopsis thaliana. PMID:25132838

  19. Gas exchange and leaf aging in an evergreen oak: causes and consequences for leaf carbon balance and canopy respiration.

    PubMed

    Rodríguez-Calcerrada, Jesús; Limousin, Jean-Marc; Martin-StPaul, Nicolas K; Jaeger, Carsten; Rambal, Serge

    2012-04-01

    Leaves of Mediterranean evergreens experience large variations in gas exchange rates over their life span due to aging and seasonally changing environmental conditions. Accounting for the changing respiratory physiology of leaves over time will help improve estimations of leaf and whole-plant carbon balances. Here we examined seasonal variations in light-saturated net CO(2) assimilation (A(max)), dark respiration (R(d)) and the proportional change in R(d) per 10 °C change in temperature (Q(10) of R(d)) in previous-year (PY) and current-year (CY) leaves of the broadleaved evergreen tree Quercus ilex L. A(max) and R(d) were lower in PY than in CY leaves. Differences in nitrogen between cohorts only partly explained such differences, and rates of A(max) and R(d) expressed per unit of leaf nitrogen were still significantly different between cohorts. The decline in A(max) in PY leaves did not result in the depletion of total non-structural carbohydrates, whose concentration was in fact higher in PY than CY leaves. Leaf-level carbon balance modeled from gas exchange data was positive at all ages. Q(10) of R(d) did not differ significantly between leaf cohorts; however, failure to account for distinct R(d) between cohorts misestimated canopy leaf respiration by 13% across dates when scaling up leaf measurements to the canopy. In conclusion, the decline in A(max) in old leaves that are close to or exceed their mean life span does not limit the availability of carbohydrates, which are probably needed to sustain new growth, as well as R(d) and nutrient resorption during senescence. Accounting for leaf age as a source of variation of R(d) improves the estimation of foliar respiratory carbon release at the stand scale.

  20. Predicting leaf physiology from simple plant and climate attributes: a global GLOPNET analysis.

    PubMed

    Reich, Peter B; Wright, Ian J; Lusk, Christopher H

    2007-10-01

    Knowledge of leaf chemistry, physiology, and life span is essential for global vegetation modeling, but such data are scarce or lacking for some regions, especially in developing countries. Here we use data from 2021 species at 175 sites around the world from the GLOPNET compilation to show that key physiological traits that are difficult to measure (such as photosynthetic capacity) can be predicted from simple qualitative plant characteristics, climate information, easily measured ("soft") leaf traits, or all of these in combination. The qualitative plant functional type (PFT) attributes examined are phylogeny (angiosperm or gymnosperm), growth form (grass, herb, shrub, or tree), and leaf phenology (deciduous vs. evergreen). These three PFT attributes explain between one-third and two-thirds of the variation in each of five quantitative leaf ecophysiological traits: specific leaf area (SLA), leaf life span, mass-based net photosynthetic capacity (Amass), nitrogen content (N(mass)), and phosphorus content (P(mass)). Alternatively, the combination of four simple, widely available climate metrics (mean annual temperature, mean annual precipitation, mean vapor pressure deficit, and solar irradiance) explain only 5-20% of the variation in those same five leaf traits. Adding the climate metrics to the qualitative PFTs as independent factors in the model increases explanatory power by 3-11% for the five traits. If a single easily measured leaf trait (SLA) is also included in the model along with qualitative plant traits and climate metrics, an additional 5-25% of the variation in the other four other leaf traits is explained, with the models accounting for 62%, 65%, 66%, and 73% of global variation in N(mass), P(mass), A(mass), and leaf life span, respectively. Given the wide availability of the summary climate data and qualitative PFT data used in these analyses, they could be used to explain roughly half of global variation in the less accessible leaf traits (A

  1. Leaf physiognomy and climate: A multivariate analysis

    NASA Astrophysics Data System (ADS)

    Davis, J. M.; Taylor, S. E.

    1980-11-01

    Research has demonstrated that leaf physiognomy is representative of the local or microclimate conditions under which plants grow. The physiognomy of leaf samples from Oregon, Michigan, Missouri, Tennessee, and the Panama Canal Zone has been related to the microclimate using Walter diagrams and Thornthwaite water-budget data. A technique to aid paleoclimatologists in identifying the nature of the microclimate from leaf physiognomy utilizes statistical procedures to classify leaf samples into one of six microclimate regimes based on leaf physiognomy information available from fossilized samples.

  2. Effect of lutein, sesamol, ellagic acid and olive leaf extract on the quality and shelf-life stability of packaged raw minced beef patties.

    PubMed

    Hayes, J E; Stepanyan, V; Allen, P; O'Grady, M N; Kerry, J P

    2010-04-01

    The effects of lutein (100 and 200 microg/g muscle), sesamol (250 and 500 microg/g muscle), ellagic acid (300 and 600 microg/g muscle) and olive leaf extract (100 and 200 microg/g muscle) on total viable counts (TVCs), lipid oxidation (thiobarbituric acid-reactive substances, TBARS), colour, oxymyoglobin oxidation, pH, water-holding capacity (WHC), sensorial properties of raw beef patties (M. longissimus thoracis et lumborum) stored in modified atmosphere packs (80% O(2):20% CO(2)) (MAP) aerobically at 4 degrees C for up to 8 and 12 days, respectively, were examined. All the nutraceuticals reduced (P<0.001) TVCs. The addition of sesamol, ellagic acid and olive leaf extract reduced (P<0.001) TBARS in raw beef patties in both packaging systems. Sesamol addition to beef resulted in lower (P<0.01) a* redness values and increased oxymyoglobin oxidation. Conversely, lutein and olive leaf extract reduced (P<0.001) oxymyoglobin oxidation relative to the control. The graded addition of ellagic acid and olive leaf extract improved (P<0.001) WHC.

  3. What evidence is available on end-of-life (EOL) care and Latino elders? A literature review.

    PubMed

    Cruz-Oliver, Dulce M; Talamantes, Melissa; Sanchez-Reilly, Sandra

    2014-02-01

    Low-income and minority persons, such as Latinos, encounter substantial barriers in accessing effective end-of-life (EOL) care. This study intends to review current evidence on how to deliver EOL care to Latino elders. Literature search in PubMed and Ovid Web sites of articles indexed in Medline (1948-2011), Cochrane (2005-2011), Embase, and PsychInfo (1967-2011) databases. Articles were included if they contained (1) study participants' race/ethnicity, (2) adults or population older than 60 years, and (3) information related to EOL care. A total of 64 abstracts were reviewed, and 38 articles met the inclusion criteria. After reviewing the quality of evidence, 4 themes were identified and summarized: EOL preferences, hospice, Latino culture, and caregiving. Latino elders have traditional acculturation practices, face EOL decisions with family support, and, if educated, are receptive toward hospice and caregiver support.

  4. A Safe-Anesthesia Innovation for Emergency and Life-Improving Surgeries When no Anesthetist is Available: A Descriptive Review of 193 Consecutive Surgeries.

    PubMed

    Burke, Thomas; Manglani, Yogeeta; Altawil, Zaid; Dickson, Alexandra; Clark, Rachel; Okelo, Stephen; Ahn, Roy

    2015-09-01

    The worldwide human resource gap in anesthesia services often presents a barrier to accessing life-saving and life-improving surgeries. This paper assessed the impact of a ketamine anesthesia package, Every Second Matters-Ketamine (ESM-Ketamine)™, for use in emergency and life-improving surgeries by non-anesthetist clinicians in a resource-limited setting when no anesthetist was available. We analyzed prospectively collected data from 193 surgeries constituting a pilot implementation of the ESM-Ketamine package, among three sub-district hospitals in Western Kenya. The study population comprises patients who required emergency or life-improving surgery when no anesthetist was available. Non-anesthetist clinicians in three sub-district hospitals underwent a 5-day training course in ESM-Ketamine complemented by checklists and an ESM-Ketamine Kit. Data were collected prospectively every time the ESM-Ketamine pathway was invoked. The training cases, although primarily tubal ligations, were included. The primary outcome measures centered on capturing the ability to safely support emergency and life-improving surgeries, when no anesthetist was available, through invoking the ESM-Ketamine pathway. The registry was critically examined using standard descriptive and frequency analysis. 193 surgical procedures were supported using the ESM-Ketamine package by five ESM-Ketamine trained providers. Brief (<30 s) patient desaturation below 92% and hallucinations occurred in 16 out of 186 (8.6%) and 23 out of 190 patients (12.1%), respectively. There were no reported major adverse events such as death, prolonged desaturations (over 30 s), or injury resulting from ketamine use. This study provides promising initial evidence that the ESM-Ketamine package can support emergency and life-improving surgeries in resource-limited settings when no anesthetist is available.

  5. Availability of Micro-Tom mutant library combined with TILLING in molecular breeding of tomato fruit shelf-life.

    PubMed

    Okabe, Yoshihiro; Asamizu, Erika; Ariizumi, Tohru; Shirasawa, Kenta; Tabata, Satoshi; Ezura, Hiroshi

    2012-06-01

    Novel mutant alleles of an ethylene receptor Solanum lycopersicum ETHYLENE RESPONSE1 (SlETR1) gene, Sletr1-1 and Sletr1-2, were isolated from the Micro-Tom mutant library by TILLING in our previous study. They displayed different levels of impaired fruit ripening phenotype, suggesting that these alleles could be a valuable breeding material for improving shelf life of tomato fruit. To conduct practical use of the Sletr1 alleles in tomato breeding, genetic complementation analysis by transformation of genes carrying each allele is required. In this study, we generated and characterized transgenic lines over-expressing Sletr1-1 and Sletr1-2. All transgenic lines displayed ethylene insensitive phenotype and ripening inhibition, indicating that Sletr1-1 and Sletr1-2 associate with the ethylene insensitive phenotype. The level of ethylene sensitivity in the seedling was different between Sletr1-1 and Sletr1-2 transgenic lines, whereas no apparent difference was observed in fruit ripening phenotype. These results suggested that it is difficult to fine-tune the extent of ripening by transgenic approach even if the weaker allele (Sletr1-2) was used. Our present and previous studies indicate that the Micro-Tom mutant library combined with TILLING could be an efficient tool for exploring genetic variations of important agronomic traits in tomato breeding.

  6. Convergence in relationships between leaf traits, spectra and age across diverse canopy environments and two contrasting tropical forests

    DOE PAGES

    Wu, Jin; Chavana-Bryant, Cecilia; Prohaska, Neill; ...

    2016-07-06

    Leaf age structures the phenology and development of plants, as well as the evolution of leaf traits over life histories. Furthermore, a general method for efficiently estimating leaf age across forests and canopy environments is lacking.

  7. News and Views: VLT detects convincing signs of life - on Earth; Lemaître honoured; Sun gets active; Earthquakes on Islay; Herschel family papers available online

    NASA Astrophysics Data System (ADS)

    2012-04-01

    European Southern Observatory data from the Very Large Telescope have enabled astronomers to say with confidence that they can detect signs of life on Earth using spectropolarimetry of earthshine: light from the Earth's atmosphere reflected from the Moon. This is an important step towards detecting life on exoplanets. A collection of archive materials from the family of Sir John F W Herschel (1792-1871) is now available for study at Harry Ransom Center at the University of Texas at Austin. The collection includes much of John Herschel's correspondence as well as examples of his cyanotypes.

  8. Towards ground-truthing of spaceborne estimates of above-ground life biomass and leaf area index in tropical rain forests

    NASA Astrophysics Data System (ADS)

    Köhler, P.; Huth, A.

    2010-08-01

    The canopy height h of forests is a key variable which can be obtained using air- or spaceborne remote sensing techniques such as radar interferometry or LIDAR. If new allometric relationships between canopy height and the biomass stored in the vegetation can be established this would offer the possibility for a global monitoring of the above-ground carbon content on land. In the absence of adequate field data we use simulation results of a tropical rain forest growth model to propose what degree of information might be generated from canopy height and thus to enable ground-truthing of potential future satellite observations. We here analyse the correlation between canopy height in a tropical rain forest with other structural characteristics, such as above-ground life biomass (AGB) (and thus carbon content of vegetation) and leaf area index (LAI) and identify how correlation and uncertainty vary for two different spatial scales. The process-based forest growth model FORMIND2.0 was applied to simulate (a) undisturbed forest growth and (b) a wide range of possible disturbance regimes typically for local tree logging conditions for a tropical rain forest site on Borneo (Sabah, Malaysia) in South-East Asia. In both undisturbed and disturbed forests AGB can be expressed as a power-law function of canopy height h (AGB = a · hb) with an r2 ~ 60% if data are analysed in a spatial resolution of 20 m × 20 m (0.04 ha, also called plot size). The correlation coefficient of the regression is becoming significant better in the disturbed forest sites (r2 = 91%) if data are analysed hectare wide. There seems to exist no functional dependency between LAI and canopy height, but there is also a linear correlation (r2 ~ 60%) between AGB and the area fraction of gaps in which the canopy is highly disturbed. A reasonable agreement of our results with observations is obtained from a comparison of the simulations with permanent sampling plot (PSP) data from the same region and with the

  9. Leaf area dynamics of conifer forests

    SciTech Connect

    Margolis, H.; Oren, R.; Whitehead, D.; Kaufmann, M.R.

    1995-07-01

    Estimating the surface area of foliage supported by a coniferous forest canopy is critical for modeling its biological properties. Leaf area represents the surface area available for the interception of energy, the absorption of carbon dioxide, and the diffusion of water from the leaf to the atmosphere. The concept of leaf area is pertinent to the physiological and ecological dynamics of conifers at a wide range of spatial scales, from individual leaves to entire biomes. In fact, the leaf area of vegetation at a global level can be thought of as a carbon-absorbing, water-emitting membrane of variable thickness, which can have an important influence on the dynamics and chemistry of the Earth`s atmosphere over both the short and the long term. Unless otherwise specified, references to leaf area herein refer to projected leaf area, i.e., the vertical projection of needles placed on a flat plane. Total leaf surface area is generally from 2.0 to 3.14 times that of projected leaf area for conifers. It has recently been suggested that hemisurface leaf area, i.e., one-half of the total surface area of a leaf, a more useful basis for expressing leaf area than is projected area. This chapter is concerned with the dynamics of coniferous forest leaf area at different spatial and temporal scales. In the first part, we consider various hypotheses related to the control of leaf area development, ranging from simple allometric relations with tree size to more complex mechanistic models that consider the movement of water and nutrients to tree canopies. In the second part, we consider various aspects of leaf area dynamics at varying spatial and temporal scales, including responses to perturbation, seasonal dynamics, genetic variation in crown architecture, the responses to silvicultural treatments, the causes and consequences of senescence, and the direct measurement of coniferous leaf area at large spatial scales using remote sensing.

  10. Life history and systematics of Albusambia elaphoglossumae (Lepidoptera: Crambidae): a new genus and species of musotimine with leaf-mining biology from Costa Rica.

    PubMed

    Solis, M Alma; Davis, Donald R; Nishida, Kenji

    2005-01-01

    Albusambia elaphoglossumae Solis & Davis, a new genus and species, is described. It was discovered mining the fronds of the fern Elaphoglossum conspersum in Costa Rica (San José and Cartago Provinces, at elevations of 2300-3100 m). The type series was obtained by rearing of the immature stages in laboratory. The adult is defined by unique genital characters, and the pupa with a medial depression on the vertex and with two anterolateral horn-like structures on the prothorax. The larva is a gregarious leaf miner with its body flattened dorsoventrally and head prognathous; morphological adaptations to its leaf-mining habit are new to the Musotiminae. Fern-feeding musotimines are important to the discovery of new biological control agents for invasive ferns.

  11. Seasonal variability of multiple leaf traits captured by leaf spectroscopy at two temperate deciduous forests

    DOE PAGES

    Yang, Xi; Tang, Jianwu; Mustard, John F.; ...

    2016-04-02

    Understanding the temporal patterns of leaf traits is critical in determining the seasonality and magnitude of terrestrial carbon, water, and energy fluxes. However, we lack robust and efficient ways to monitor the temporal dynamics of leaf traits. Here we assessed the potential of leaf spectroscopy to predict and monitor leaf traits across their entire life cycle at different forest sites and light environments (sunlit vs. shaded) using a weekly sampled dataset across the entire growing season at two temperate deciduous forests. In addition, the dataset includes field measured leaf-level directional-hemispherical reflectance/transmittance together with seven important leaf traits [total chlorophyll (chlorophyllmore » a and b), carotenoids, mass-based nitrogen concentration (Nmass), mass-based carbon concentration (Cmass), and leaf mass per area (LMA)]. All leaf traits varied significantly throughout the growing season, and displayed trait-specific temporal patterns. We used a Partial Least Square Regression (PLSR) modeling approach to estimate leaf traits from spectra, and found that PLSR was able to capture the variability across time, sites, and light environments of all leaf traits investigated (R2 = 0.6–0.8 for temporal variability; R2 = 0.3–0.7 for cross-site variability; R2 = 0.4–0.8 for variability from light environments). We also tested alternative field sampling designs and found that for most leaf traits, biweekly leaf sampling throughout the growing season enabled accurate characterization of the seasonal patterns. Compared with the estimation of foliar pigments, the performance of Nmass, Cmass and LMA PLSR models improved more significantly with sampling frequency. Our results demonstrate that leaf spectra-trait relationships vary with time, and thus tracking the seasonality of leaf traits requires statistical models calibrated with data sampled throughout the growing season. In conclusion, our results have broad implications for future

  12. Gallium-68 -- a new opportunity for PET available from a long shelf-life generator - automation and applications.

    PubMed

    Decristoforo, Clemens

    2012-07-01

    (68)Ge/(68)Ga generators have received tremendous attention in the last years based on the success of (68)Ga-labelled Somatostatin analogues for Positron-Emission Tomography (PET), which are today used routinely worldwide. Various commercially available generator types are based on different column matrices including TiO(2), SnO(2) or organic (68)Gechelate coated silica, providing (68)Ga as Ga(3+) in HCl for radiolabeling procedures. These systems can serve as a stable source of (68)Ga for PET applications over periods of more than one year with high yields. A number of methods for post processing of the eluate including fractionation, anion or cation exchange purification have been developed. These methods are particularly important for high specific activity labeling of biomolecules such as peptides ensuring small volumes, low metallic contamination and low (68)Ge breakthrough. These systems have been implemented into fully automated modules allowing generator elution, post processing radiolabeling and formulation, complying with high regulatory demands. Quality aspects regarding the clinical use of (68)Ga for patient applications including limit of (68)Ge content, metal contamination, microbiological safety and radiochemical purity have been addressed. Overall, the establishment of (68)Ge/(68)Ga generator technology together with the development of novel (68)Ga-radiopharmaceuticals make (68)Ga a most promising radionuclide for PET in the years to come.

  13. Ecological differentiation in xylem cavitation resistance is associated with stem and leaf structural traits.

    PubMed

    Markesteijn, Lars; Poorter, Lourens; Paz, Horacio; Sack, Lawren; Bongers, Frans

    2011-01-01

    Cavitation resistance is a critical determinant of drought tolerance in tropical tree species, but little is known of its association with life history strategies, particularly for seasonal dry forests, a system critically driven by variation in water availability. We analysed vulnerability curves for saplings of 13 tropical dry forest tree species differing in life history and leaf phenology. We examined how vulnerability to cavitation (P₅₀) related to dry season leaf water potentials and stem and leaf traits. P₅₀-values ranged from -0.8 to -6.2 MPa, with pioneers on average 38% more vulnerable to cavitation than shade-tolerants. Vulnerability to cavitation was related to structural traits conferring tissue stress vulnerability, being negatively correlated with wood density, and surprisingly maximum vessel length. Vulnerability to cavitation was negatively related to the Huber-value and leaf dry matter content, and positively with leaf size. It was not related to SLA. We found a strong trade-off between cavitation resistance and hydraulic efficiency. Most species in the field were operating at leaf water potentials well above their P₅₀, but pioneers and deciduous species had smaller hydraulic safety margins than shade-tolerants and evergreens. A trade-off between hydraulic safety and efficiency underlies ecological differentiation across these tropical dry forest tree species.

  14. Reaction of sorghum lines to zonate leaf spot and rough leaf spot

    USDA-ARS?s Scientific Manuscript database

    Abundant, frequent rains, along with humid and cloudy conditions during the early part of the 2015 growing season, provided conducive conditions for an unusually severe outbreak of zonate leaf spot and rough leaf spot in a block of sorghum lines at the Texas A&M AgriLife Research Farm, Burleson Coun...

  15. Blade life span, structural investment, and nutrient allocation in giant kelp.

    PubMed

    Rodriguez, Gabriel E; Reed, Daniel C; Holbrook, Sally J

    2016-10-01

    The turnover of plant biomass largely determines the amount of energy flowing through an ecosystem and understanding the processes that regulate turnover has been of interest to ecologists for decades. Leaf life span theory has proven useful in explaining patterns of leaf turnover in relation to resource availability, but the predictions of this theory have not been tested for macroalgae. We measured blade life span, size, thickness, nitrogen content, pigment content, and maximum photosynthetic rate (P max) in the giant kelp (Macrocystis pyrifera) along a strong resource (light) gradient to test whether the predictions of leaf life span theory applied to this alga. We found that shorter blade life spans and larger blade areas were associated with increased light availability. In addition, nitrogen and P max decreased with blade age, and their decrease was greater in shorter lived blades. These observations are generally consistent with patterns observed for higher plants and the prevailing theory of leaf life span. By contrast, variation observed in pigments of giant kelp was inconsistent with that predicted by leaf life span theory, as blades growing in the most heavily shaded portion of the forest had the lowest chlorophyll content. This result may reflect the dual role of macroalgal blades in carbon fixation and nutrient absorption and the ability of giant kelp to modify blade physiology to optimize the acquisition of light and nutrients. Thus, the marine environment may place demands on resource acquisition and allocation that have not been previously considered with respect to leaf life span optimization.

  16. Why do leaf-tying caterpillars abandon their leaf ties?

    PubMed Central

    Sliwinski, Michelle

    2013-01-01

    Leaf-tying caterpillars act as ecosystem engineers by building shelters between overlapping leaves, which are inhabited by other arthropods. Leaf-tiers have been observed to leave their ties and create new shelters (and thus additional microhabitats), but the ecological factors affecting shelter fidelity are poorly known. For this study, we explored the effects of resource limitation and occupant density on shelter fidelity and assessed the consequences of shelter abandonment. We first quantified the area of leaf material required for a caterpillar to fully develop for two of the most common leaf-tiers that feed on white oak, Quercus alba. On average, Psilocorsis spp. caterpillars consumed 21.65 ± 0.67 cm2 leaf material to complete development. We also measured the area of natural leaf ties found in a Maryland forest, to determine the distribution of resources available to caterpillars in situ. Of 158 natural leaf ties examined, 47% were too small to sustain an average Psilocorsis spp. caterpillar for the entirety of its development. We also manipulated caterpillar densities within experimental ties on potted trees to determine the effects of cohabitants on the likelihood of a caterpillar to leave its tie. We placed 1, 2, or 4 caterpillars in ties of a standard size and monitored the caterpillars twice daily to track their movement. In ties with more than one occupant, caterpillars showed a significantly greater propensity to leave their tie, and left sooner and at a faster rate than those in ties as single occupants. To understand the consequences of leaf tie abandonment, we observed caterpillars searching a tree for a site to build a shelter in the field. This is a risky behavior, as 17% of the caterpillars observed died while searching for a shelter site. Caterpillars that successfully built a shelter traveled 110 ± 20 cm and took 28 ± 7 min to find a suitable site to build a shelter. In conclusion, leaf-tying caterpillars must frequently abandon their leaf

  17. Why do leaf-tying caterpillars abandon their leaf ties?

    PubMed

    Sliwinski, Michelle; Sigmon, Elisha

    2013-01-01

    Leaf-tying caterpillars act as ecosystem engineers by building shelters between overlapping leaves, which are inhabited by other arthropods. Leaf-tiers have been observed to leave their ties and create new shelters (and thus additional microhabitats), but the ecological factors affecting shelter fidelity are poorly known. For this study, we explored the effects of resource limitation and occupant density on shelter fidelity and assessed the consequences of shelter abandonment. We first quantified the area of leaf material required for a caterpillar to fully develop for two of the most common leaf-tiers that feed on white oak, Quercus alba. On average, Psilocorsis spp. caterpillars consumed 21.65 ± 0.67 cm(2) leaf material to complete development. We also measured the area of natural leaf ties found in a Maryland forest, to determine the distribution of resources available to caterpillars in situ. Of 158 natural leaf ties examined, 47% were too small to sustain an average Psilocorsis spp. caterpillar for the entirety of its development. We also manipulated caterpillar densities within experimental ties on potted trees to determine the effects of cohabitants on the likelihood of a caterpillar to leave its tie. We placed 1, 2, or 4 caterpillars in ties of a standard size and monitored the caterpillars twice daily to track their movement. In ties with more than one occupant, caterpillars showed a significantly greater propensity to leave their tie, and left sooner and at a faster rate than those in ties as single occupants. To understand the consequences of leaf tie abandonment, we observed caterpillars searching a tree for a site to build a shelter in the field. This is a risky behavior, as 17% of the caterpillars observed died while searching for a shelter site. Caterpillars that successfully built a shelter traveled 110 ± 20 cm and took 28 ± 7 min to find a suitable site to build a shelter. In conclusion, leaf-tying caterpillars must frequently abandon their leaf

  18. Effects of growth rate, size, and light availability on tree survival across life stages: a demographic analysis accounting for missing values and small sample sizes.

    PubMed

    Moustakas, Aristides; Evans, Matthew R

    2015-02-28

    Plant survival is a key factor in forest dynamics and survival probabilities often vary across life stages. Studies specifically aimed at assessing tree survival are unusual and so data initially designed for other purposes often need to be used; such data are more likely to contain errors than data collected for this specific purpose. We investigate the survival rates of ten tree species in a dataset designed to monitor growth rates. As some individuals were not included in the census at some time points we use capture-mark-recapture methods both to allow us to account for missing individuals, and to estimate relocation probabilities. Growth rates, size, and light availability were included as covariates in the model predicting survival rates. The study demonstrates that tree mortality is best described as constant between years and size-dependent at early life stages and size independent at later life stages for most species of UK hardwood. We have demonstrated that even with a twenty-year dataset it is possible to discern variability both between individuals and between species. Our work illustrates the potential utility of the method applied here for calculating plant population dynamics parameters in time replicated datasets with small sample sizes and missing individuals without any loss of sample size, and including explanatory covariates.

  19. Tryptophan availability for kynurenine pathway metabolism across the life span: Control mechanisms and focus on aging, exercise, diet and nutritional supplements.

    PubMed

    Badawy, Abdulla A-B

    2017-01-01

    Tryptophan (Trp) availability for the kynurenine pathway (KP) across the life span is discussed. Free (non-albumin-bound) plasma Trp is the major determinant of the flux of Trp down the KP. Flux is the major determinant of kynurenine metabolite formation and is more effective than induction of hepatic Trp 2,3-dioxygenase (TDO) or extrahepatic indoleamine 2,3-dioxygenase (IDO). Flux is better expressed using the sum of plasma kynurenine and its metabolites, rather than kynurenine only. Under normal conditions, TDO controls Trp flux in liver and availability in plasma and can supply kynurenine for the extrahepatic pathway. Under certain pathological conditions associated with immune activation, IDO assumes the major role in control of Trp availability. Plasma Trp availability is increased during pregnancy, at birth, and by exercise, high protein and fat intake. Aging does not seem to exert a major effect on plasma Trp. Assessment of plasma Trp availability in health and disease requires measurement of concentrations of both free and total [Trp] in the first instance, followed, if necessary, by those of albumin and the physiological displacers of albumin-bound Trp, non-esterified fatty acids. Additional measures should include cortisol, cytokines, kynurenine and its metabolites. This article is part of the Special Issue entitled 'The Kynurenine Pathway in Health and Disease'. Copyright © 2015 Elsevier Ltd. All rights reserved.

  20. Active suppression of a leaf meristem orchestrates determinate leaf growth

    PubMed Central

    Alvarez, John Paul; Furumizu, Chihiro; Efroni, Idan; Eshed, Yuval; Bowman, John L

    2016-01-01

    Leaves are flat determinate organs derived from indeterminate shoot apical meristems. The presence of a specific leaf meristem is debated, as anatomical features typical of meristems are not present in leaves. Here we demonstrate that multiple NGATHA (NGA) and CINCINNATA-class-TCP (CIN-TCP) transcription factors act redundantly, shortly after leaf initiation, to gradually restrict the activity of a leaf meristem in Arabidopsis thaliana to marginal and basal domains, and that their absence confers persistent marginal growth to leaves, cotyledons and floral organs. Following primordia initiation, the restriction of the broadly acting leaf meristem to the margins is mediated by the juxtaposition of adaxial and abaxial domains and maintained by WOX homeobox transcription factors, whereas other marginal elaboration genes are dispensable for its maintenance. This genetic framework parallels the morphogenetic program of shoot apical meristems and may represent a relic of an ancestral shoot system from which seed plant leaves evolved. DOI: http://dx.doi.org/10.7554/eLife.15023.001 PMID:27710768

  1. Contrasting seasonal leaf habits of canopy trees between tropical dry-deciduous and evergreen forests in Thailand.

    PubMed

    Ishida, Atsushi; Diloksumpun, Sapit; Ladpala, Phanumard; Staporn, Duriya; Panuthai, Samreong; Gamo, Minoru; Yazaki, Kenichi; Ishizuka, Moriyoshi; Puangchit, Ladawan

    2006-05-01

    We compared differences in leaf properties, leaf gas exchange and photochemical properties between drought-deciduous and evergreen trees in tropical dry forests, where soil nutrients differed but rainfall was similar. Three canopy trees (Shorea siamensis Miq., Xylia xylocarpa (Roxb.) W. Theob. and Vitex peduncularis Wall. ex Schauer) in a drought-deciduous forest and a canopy tree (Hopea ferrea Lanessan) in an evergreen forest were selected. Soil nutrient availability is lower in the evergreen forest than in the deciduous forest. Compared with the evergreen tree, the deciduous trees had shorter leaf life spans, lower leaf masses per area, higher leaf mass-based nitrogen (N) contents, higher leaf mass-based photosynthetic rates (mass-based P(n)), higher leaf N-based P(n), higher daily maximum stomatal conductance (g(s)) and wider conduits in wood xylem. Mass-based P(n) decreased from the wet to the dry season for all species. Following onset of the dry season, daily maximum g(s) and sensitivity of g(s) to leaf-to-air vapor pressure deficit remained relatively unchanged in the deciduous trees, whereas both properties decreased in the evergreen tree during the dry season. Photochemical capacity and non-photochemical quenching (NPQ) of photosystem II (PSII) also remained relatively unchanged in the deciduous trees even after the onset of the dry season. In contrast, photochemical capacity decreased and NPQ increased in the evergreen tree during the dry season, indicating that the leaves coped with prolonged drought by down-regulating PSII. Thus, the drought-avoidant deciduous species were characterized by high N allocation for leaf carbon assimilation, high water use and photoinhibition avoidance, whereas the drought-tolerant evergreen was characterized by low N allocation for leaf carbon assimilation, conservative water use and photoinhibition tolerance.

  2. Do Substance Use Norms and Perceived Drug Availability Mediate Sexual Orientation Differences in Patterns of Substance Use? Results from the California Quality of Life Survey II

    PubMed Central

    Cochran, Susan D.; Grella, Christine E.; Mays, Vickie M.

    2012-01-01

    Objective: Illicit drug and heavy alcohol use is more common among sexual minorities compared with heterosexuals. This difference has sometimes been attributed to more tolerant substance use norms within the gay community, although evidence is sparse. The current study investigated the role of perceived drug availability and tolerant injunctive norms in mediating the linkage between minority sexual orientation status and higher rates of prior-year substance use. Method: We used data from the second California Quality of Life Survey (Cal-QOL II), a followback telephone survey in 2008–2009 of individuals first interviewed in the population-based 2007 California Health Interview Survey. The sample comprised 2,671 individuals, oversampled for minority sexual orientation. Respondents were administered a structured interview assessing past-year alcohol and illicit drug use, perceptions of perceived illicit drug availability, and injunctive norms concerning illicit drug and heavier alcohol use. We used structural equation modeling methods to test a mediational model linking sexual orientation and substance use behaviors via perceptions of drug availability and social norms pertaining to substance use. Results: Compared with heterosexual individuals, sexual minorities reported higher levels of substance use, perceived drug availability, and tolerant social norms. A successfully fitting model suggests that much of the association between minority sexual orientation and substance use is mediated by these sexual orientation–related differences in drug availability perceptions and tolerant norms for substance use. Conclusions: Social environmental context, including subcultural norms and perceived drug availability, is an important factor influencing substance use among sexual minorities and should be addressed in community interventions. PMID:22630806

  3. Coping with an unpredictable and stressful environment: the life history and metabolic response to variable food and host availability in a polyphagous tephritid fly.

    PubMed

    Aluja, Martín; Birke, Andrea; Guillén, Larissa; Díaz-Fleischer, Francisco; Nestel, David

    2011-12-01

    The way energy resources are used under variable environmental conditions lies at the heart of our understanding of resource management and opportunism in many organisms. Here we sought to determine how a time-limited, synovigenic and polyphagous insect with a high reproductive-potential (Anastrephaludens), copes behaviourally and metabolically with environmental unpredictability represented by constant and variable regimes of host availability and variation in food quality. We hypothesized that an adaptive response to a windfall of nutritious food would be the rapid accumulation of energy metabolites (whole body lipids, glycogen and proteins) in the female. We also studied patterns of oogenesis as an indicator of egg-reabsorption under stressful environmental conditions. As predicted, patterns of energy metabolites were mainly driven by the quality and temporal pattern of food availability. In contrast, patterns of host availability had a lower impact upon metabolites. When given constant access to high quality nutrients, after an initial increase early in life, whole body lipids and glycogen were regulated downward to a steady-state level and somatic protein levels did not vary. In contrast, when food uncertainty was introduced, whole body lipid, glycogen and protein oscillated sharply with peaks associated with pulses of high-quality food. Production of eggs was highest when offered continuous access to hosts and high quality food. Importantly, females fully recovered their reproductive capacity when fruit became available following a period of host deprivation. With no evidence of egg resorption and high levels of egg dumping, it appears that egg dumping may favour the continuous production of eggs such that the female's reproductive tissues are ready to respond to rapid changes in the availability of hosts. Our results exemplify the capacity of insects to maximize reproduction under variable and stressful environmental conditions. Copyright © 2011 Elsevier

  4. Are leaf physiological traits related to leaf water isotopic enrichment in restinga woody species?

    PubMed

    Rosado, Bruno H P; De Mattos, Eduardo A; Sternberg, Leonel Da S L

    2013-09-01

    During plant-transpiration, water molecules having the lighter stable isotopes of oxygen and hydrogen evaporate and diffuse at a faster rate through the stomata than molecules having the heavier isotopes, which cause isotopic enrichment of leaf water. Although previous models have assumed that leaf water is well-mixed and isotopically uniform, non-uniform stomatal closure, promoting different enrichments between cells, and different pools of water within leaves, due to morpho-physiological traits, might lead to inaccuracies in isotopic models predicting leaf water enrichment. We evaluate the role of leaf morpho-physiological traits on leaf water isotopic enrichment in woody species occurring in a coastal vegetation of Brazil known as restinga. Hydrogen and oxygen stable isotope values of soil, plant stem and leaf water and leaf traits were measured in six species from restinga vegetation during a drought and a wet period. Leaf water isotopic enrichment relative to stem water was more homogeneous among species during the drought in contrast to the wet period suggesting convergent responses to deal to temporal heterogeneity in water availability. Average leaf water isotopic enrichment relative to stem water during the drought period was highly correlated with relative apoplastic water content. We discuss this observation in the context of current models of leaf water isotopic enrichment as a function of the Péclet effect. We suggest that future studies should include relative apoplastic water content in isotopic models.

  5. Long term leaf phenology and leaf exchange strategies of a cerrado savanna community

    NASA Astrophysics Data System (ADS)

    de Camargo, Maria Gabriela G.; Costa Alberton, Bruna; de Carvalho, Gustavo H.; Magalhães, Paula A. N. R.; Morellato, Leonor Patrícia C.

    2017-04-01

    Leaf development and senescence cycles are linked to a range of ecosystem processes, affecting seasonal patterns of atmosphere-ecosystem carbon and energy exchanges, resource availability and nutrient cycling. The degree of deciduousness of tropical trees and communities depend on ecosystems characteristics such as amount of biomass, species diversity and the strength and length of the dry season. Besides defining the growing season, deciduousness can also be an indicator of species response to climate changes in the tropics, mainly because severity of dry season can intensify leaf loss. Based on seven-years of phenological observations (2005 to 2011) we describe the long-term patterns of leafing phenology of a Brazilian cerrado savanna, aiming to (i) identify leaf exchange strategies of species, quantifying the degree of deciduousness, and verify whether these strategies vary among years depending on the length and strength of the dry seasons; (ii) define the growing seasons along the years and the main drivers of leaf flushing in the cerrado. We analyzed leafing patterns of 107 species and classified 69 species as deciduous (11 species), semi-deciduous (29) and evergreen (29). Leaf exchange was markedly seasonal, as expected for seasonal tropical savannas. Leaf fall predominated in the dry season, peaking in July, and leaf flushing in the transition between dry to wet seasons, peaking in September. Leafing patterns were similar among years with the growing season starting at the end of dry season, in September, for most species. However, leaf exchange strategies varied among years for most species (65%), except for evergreen strategy, mainly constant over years. Leafing patterns of cerrado species were strongly constrained by rainfall. The length of the dry season and rainfall intensity were likely affecting the individuals' leaf exchange strategies and suggesting a differential resilience of species to changes of rainfall regime, predicted on future global

  6. Genetically based polymorphisms in morphology and life history associated with putative host races of the water lily leaf beetle, Galerucella nymphaeae.

    PubMed

    Pappers, Stephanie M; van der Velde, Gerard; Ouborg, N Joop; van Groenendael, Jan M

    2002-08-01

    A host race is a population that is partially reproductively isolated from other conspecific populations as a direct consequence of adaptation to a specific host. The initial step in host race formation is the establishment of genetically based polymorphisms in, for example, morphology, preference, or performance. In this study we investigated whether polymorphisms observed in Galerucella nymphaeae have a genetic component. Galerucella nymphaeae, the water lily leaf beetle, is a herbivore which feeds and oviposits on the plant hosts Nuphar lutea and Nymphaea alba (both Nymphaeaceae) and Rumex hydrolapathum and Polygonum amphibium (both Polygonaceae). A full reciprocal crossing scheme (16 crosses, each replicated 10 times) and subsequent transplantation of 1,001 egg clutches revealed a genetic basis for differences in body length and mandibular width. The heritability value of these traits, based on midparent-offspring regression, ranged between 0.53 and 0.83 for the different diets. Offspring from Nymphaeaceae parents were on average 12% larger and had on average 18% larger mandibles than offspring from Polygonaceae parents. Furthermore, highly significant correlations were found between feeding preference of the offspring and the feeding preference of their parents. Finally, two fitness components were measured: development time and survival. Development time was influenced by diet, survival both by cross type and diet, the latter of which suggest adaptation of the beetles. This suggestion is strengthened by a highly significant cross x diet interaction effect for development time as well as for survival, which is generally believed to indicate local adaptation. Although no absolute genetic incompatibility among putative host races was observed, survival of the between-host family offspring, on each diet separately, was lower than the survival of the within-host family offspring on that particular host. Survival of offspring of two Nymphaeaceae parents was about

  7. Biophysical control of leaf temperature

    NASA Astrophysics Data System (ADS)

    Dong, N.; Prentice, I. C.; Wright, I. J.

    2014-12-01

    In principle sunlit leaves can maintain their temperatures within a narrower range than ambient temperatures. This is an important and long-known (but now overlooked) prediction of energy balance theory. Net radiation at leaf surface in steady state (which is reached rapidly) must be equal to the combination of sensible and latent heat exchanges with surrounding air, the former being proportional to leaf-to-air temperature difference (ΔT), the latter to the transpiration rate. We present field measurements of ΔT which confirm the existence of a 'crossover temperature' in the 25-30˚C range for species in a tropical savanna and a tropical rainforest environment. This finding is consistent with a simple representation of transpiration as a function of net radiation and temperature (Priestley-Taylor relationship) assuming an entrainment factor (ω) somewhat greater than the canonical value of 0.26. The fact that leaves in tropical forests are typically cooler than surrounding air, often already by solar noon, is consistent with a recently published comparison of MODIS day-time land-surface temperatures with air temperatures. Theory further predicts a strong dependence of leaf size (which is inversely related to leaf boundary-layer conductance, and therefore to absolute magnitude of ΔT) on moisture availability. Theoretically, leaf size should be determined by either night-time constraints (risk of frost damage to active leaves) or day-time constraints (risk of heat stress damage),with the former likely to predominate - thereby restricting the occurrence of large leaves - at high latitudes. In low latitudes, daytime maximum leaf size is predicted to increase with temperature, provided that water is plentiful. If water is restricted, however, transpiration cannot proceed at the Priestley-Taylor rate, and it quickly becomes advantageous for plants to have small leaves, which do not heat up much above the temperature of their surroundings. The difference between leaf

  8. Seasonal variability of multiple leaf traits captured by leaf spectroscopy at two temperate deciduous forests

    SciTech Connect

    Yang, Xi; Tang, Jianwu; Mustard, John F.; Wu, Jin; Zhao, Kaiguang; Serbin, Shawn; Lee, Jung-Eun

    2016-04-02

    Understanding the temporal patterns of leaf traits is critical in determining the seasonality and magnitude of terrestrial carbon, water, and energy fluxes. However, we lack robust and efficient ways to monitor the temporal dynamics of leaf traits. Here we assessed the potential of leaf spectroscopy to predict and monitor leaf traits across their entire life cycle at different forest sites and light environments (sunlit vs. shaded) using a weekly sampled dataset across the entire growing season at two temperate deciduous forests. In addition, the dataset includes field measured leaf-level directional-hemispherical reflectance/transmittance together with seven important leaf traits [total chlorophyll (chlorophyll a and b), carotenoids, mass-based nitrogen concentration (Nmass), mass-based carbon concentration (Cmass), and leaf mass per area (LMA)]. All leaf traits varied significantly throughout the growing season, and displayed trait-specific temporal patterns. We used a Partial Least Square Regression (PLSR) modeling approach to estimate leaf traits from spectra, and found that PLSR was able to capture the variability across time, sites, and light environments of all leaf traits investigated (R2 = 0.6–0.8 for temporal variability; R2 = 0.3–0.7 for cross-site variability; R2 = 0.4–0.8 for variability from light environments). We also tested alternative field sampling designs and found that for most leaf traits, biweekly leaf sampling throughout the growing season enabled accurate characterization of the seasonal patterns. Compared with the estimation of foliar pigments, the performance of Nmass, Cmass and LMA PLSR models improved more significantly with sampling frequency. Our results demonstrate that leaf spectra-trait relationships vary with time, and thus tracking the seasonality of leaf traits requires statistical models calibrated with data sampled throughout the growing season

  9. Coordinated changes in photosynthesis, water relations and leaf nutritional traits of canopy trees along a precipitation gradient in lowland tropical forest.

    PubMed

    Santiago, Louis S; Kitajima, Kaoru; Wright, S Joseph; Mulkey, Stephen S

    2004-05-01

    We investigated leaf physiological traits of dominant canopy trees in four lowland Panamanian forests with contrasting mean annual precipitation (1,800, 2,300, 3,100 and 3,500 mm). There was near complete turn-over of dominant canopy tree species among sites, resulting in greater dominance of evergreen species with long-lived leaves as precipitation increased. Mean structural and physiological traits changed along this gradient as predicted by cost-benefit theories of leaf life span. Nitrogen content per unit mass (Nmass) and light- and CO2-saturated photosynthetic rates per unit mass (Pmass) of upper canopy leaves decreased with annual precipitation, and these changes were partially explained by increasing leaf thickness and decreasing specific leaf area (SLA). Comparison of 1,800 mm and 3,100 mm sites, where canopy access was available through the use of construction cranes, revealed an association among extended leaf longevity, greater structural defense, higher midday leaf water potential, and lower Pmass, Nmass, and SLA at wetter sites. Shorter leaf life spans and more enriched foliar delta15N values in drier sites suggest greater resorption and re-metabolism of leaf N in drier forest. Greater dominance of short-lived leaves with relatively high Pmass in drier sites reflects a strategy to maximize photosynthesis when water is available and to minimize water loss and respiration costs during rainless periods. Overall, our study links coordinated change in leaf functional traits that affect productivity and nutrient cycling to seasonality in lowland tropical forests. Copyright 2004 Springer-Verlag

  10. Methods for Assessing the Impact of Fog Oil Smoke on Availability, Palatability, & Food Quality of Relevant Life Stages of Insects for Threatened and Endangered Species

    SciTech Connect

    Driver, Crystal J.; Strenge, Dennis L.; Su, Yin-Fong; Cullinan, Valerie I.; Herrington, Ricky S.; Saunders, Danielle L.; Rogers, Lee E.

    2007-04-01

    A methodology for quantifying population dynamics and food source value of insect fauna in areas subjected to fog oil smoke was developed. Our approach employed an environmentally controlled re-circulating wind tunnel outfitted with a high-heat vaporization and re-condensation fog oil generator that has been shown to produce aerosols of comparable chemistry and droplet-size distribution as those of field releases of the smoke. This method provides reproducible exposures of insects under realistic climatic and environmental conditions to fog oil aerosols that duplicate chemical and droplet-size characteristics of field releases of the smoke. The responses measured take into account reduction in food sources due to death and to changes in availability of relevant life stages of insects that form the prey base for the listed Threatened and Endangered Species. The influence of key environmental factors, wind speed and canopy structure on these responses were characterized. Data generated using this method was used to develop response functions related to particle size, concentration, wind speed, and canopy structure that will allow military personnel to assess and manage impacts to endangered species from fog oil smoke used in military training.

  11. [Not Available].

    PubMed

    Bentué-Ferrer, Danièle; Tribut, Olivier; Verdier, Marie-Clémence

    2010-01-01

    Valproic acid is an anticonvulsant drug available in France since 1967. It is a broad spectrum molecule indicated in various forms of epilepsy of the adult and the child, but it is also prescribed in the treatment of different other pathologies of nervous system. The divalproate sodium is indicated in the treatment of bipolar disorders. The valproic acid is marketed under various pharmaceutical forms, with different corresponding tmax values. But, whatever the administered preparation, the circulating active molecule is the ion valproate. Elimination half-life is from 11 to 20 h. Metabolization of valproate is important and represents its main route of elimination. Valpromide is comparable to a prodrug which metabolizes in valproate. The inter and intraindividual variability of the plasma concentrations are important. Several studies show a concentration-effect relationship, but two interventional trials ended in the lack of interest of the Therapeutic Drug Monitoring (TDM), although it is of current practice. However, numerous drug interactions may modify the plasma concentrations of valproate. The therapeutic range is from 50 to 100 mg/L (346 - 693 μmol/L). The level of proof of the interest of the TDM for this molecule was estimated in: recommended.

  12. [Not Available].

    PubMed

    Bentué-Ferrer, Danièle; Tribut, Olivier; Verdier, Marie-Clémence; Debruyne, Danièle

    2010-01-01

    Clobazam is a 1,5 benzodiazepine available in France since 1975, used in add-on with the other anticonvulsant drugs in the treatment of refractory epilepsies of child and adult and for the treatment of anxiety of adult. It is mainly metabolized in desmethylclobazam, or norclobazam, active metabolite, present in a concentration approximately eight times superior to that of the parent drug, but with an activity of the order of 20 to 40% of that of clobazam. Elimination half-life of clobazam is of 18 h while that of norclobazam is from 40 to 50 h. There is a large interindividual variability in the plasma concentrations. Furthermore, clobazam being prescribed in add-on with the other anticonvulsant drugs in resistant epilepsies, concentration-effect relationship is difficult to bring to light, since, in many studies, the patients who did not answer received the highest doses. Adverse reactions are moderated, appearing more often for the highest concentrations; also the phenomenon of tolerance seems more frequent in high concentrations. However, because of the kinetic interactions, a dosage of clobazam and norclobazam can be useful in certain cases. There is no validated therapeutic range, but the usual concentrations are in the range of 100-300 μg/L for the parent drug and about ten times more for the metabolite. The level of proof of the interest of the Therapeutic Drug Monitoring for this molecule is estimated in: rather useless.

  13. Leaf mineral nutrient remobilization during leaf senescence and modulation by nutrient deficiency

    PubMed Central

    Maillard, Anne; Diquélou, Sylvain; Billard, Vincent; Laîné, Philippe; Garnica, Maria; Prudent, Marion; Garcia-Mina, José-Maria; Yvin, Jean-Claude; Ourry, Alain

    2015-01-01

    Higher plants have to cope with fluctuating mineral resource availability. However, strategies such as stimulation of root growth, increased transporter activities, and nutrient storage and remobilization have been mostly studied for only a few macronutrients. Leaves of cultivated crops (Zea mays, Brassica napus, Pisum sativum, Triticum aestivum, Hordeum vulgare) and tree species (Quercus robur, Populus nigra, Alnus glutinosa) grown under field conditions were harvested regularly during their life span and analyzed to evaluate the net mobilization of 13 nutrients during leaf senescence. While N was remobilized in all plant species with different efficiencies ranging from 40% (maize) to 90% (wheat), other macronutrients (K–P–S–Mg) were mobilized in most species. Ca and Mn, usually considered as having low phloem mobility were remobilized from leaves in wheat and barley. Leaf content of Cu–Mo–Ni–B–Fe–Zn decreased in some species, as a result of remobilization. Overall, wheat, barley and oak appeared to be the most efficient at remobilization while poplar and maize were the least efficient. Further experiments were performed with rapeseed plants subjected to individual nutrient deficiencies. Compared to field conditions, remobilization from leaves was similar (N–S–Cu) or increased by nutrient deficiency (K–P–Mg) while nutrient deficiency had no effect on Mo–Zn–B–Ca–Mn, which seemed to be non-mobile during leaf senescence under field conditions. However, Ca and Mn were largely mobilized from roots (-97 and -86% of their initial root contents, respectively) to shoots. Differences in remobilization between species and between nutrients are then discussed in relation to a range of putative mechanisms. PMID:26029223

  14. Leaf mineral nutrient remobilization during leaf senescence and modulation by nutrient deficiency.

    PubMed

    Maillard, Anne; Diquélou, Sylvain; Billard, Vincent; Laîné, Philippe; Garnica, Maria; Prudent, Marion; Garcia-Mina, José-Maria; Yvin, Jean-Claude; Ourry, Alain

    2015-01-01

    Higher plants have to cope with fluctuating mineral resource availability. However, strategies such as stimulation of root growth, increased transporter activities, and nutrient storage and remobilization have been mostly studied for only a few macronutrients. Leaves of cultivated crops (Zea mays, Brassica napus, Pisum sativum, Triticum aestivum, Hordeum vulgare) and tree species (Quercus robur, Populus nigra, Alnus glutinosa) grown under field conditions were harvested regularly during their life span and analyzed to evaluate the net mobilization of 13 nutrients during leaf senescence. While N was remobilized in all plant species with different efficiencies ranging from 40% (maize) to 90% (wheat), other macronutrients (K-P-S-Mg) were mobilized in most species. Ca and Mn, usually considered as having low phloem mobility were remobilized from leaves in wheat and barley. Leaf content of Cu-Mo-Ni-B-Fe-Zn decreased in some species, as a result of remobilization. Overall, wheat, barley and oak appeared to be the most efficient at remobilization while poplar and maize were the least efficient. Further experiments were performed with rapeseed plants subjected to individual nutrient deficiencies. Compared to field conditions, remobilization from leaves was similar (N-S-Cu) or increased by nutrient deficiency (K-P-Mg) while nutrient deficiency had no effect on Mo-Zn-B-Ca-Mn, which seemed to be non-mobile during leaf senescence under field conditions. However, Ca and Mn were largely mobilized from roots (-97 and -86% of their initial root contents, respectively) to shoots. Differences in remobilization between species and between nutrients are then discussed in relation to a range of putative mechanisms.

  15. Leaf Size in Swietenia

    Treesearch

    Charles B. Briscoe; F. Bruce. Lamb

    1962-01-01

    A study was made of the putative hybrid of bigleaf and small-leaf mahoganies. Initial measurements indicated that bigleaf mahogany can be distinguished from small-leaf mahogany by gross measurements of leaflets. Isolated mother trees yield typical progeny. Typical mother trees in mixed stands yield like progeny plus, usually, mediumleaf progeny. Mediumleaf mother trees...

  16. Quality of life after acute myocardial infarction among patients treated at sites with and without on-site availability of angiography.

    PubMed

    Pilote, Louise; Lauzon, Claude; Huynh, Thao; Dion, Danielle; Roux, René; Racine, Normand; Carignan, Suzanne; Diodati, Jean G; Lévesque, Claude; Charbonneau, François; Pouliot, Joël; Joseph, Lawrence; Eisenberg, Mark J

    2002-03-11

    Previous studies have compared the treatment and outcome of patients with acute myocardial infarction (AMI) admitted at sites with and without availability of angiography. Although mortality rates do not differ, it is unknown if quality of life (QOL) and functional status differ. We measured QOL and functional status in patients with AMI treated within Québec at 5 sites with (n = 253) and 5 sites without (n = 334) angiography. At admission, clinical characteristics, complication rates, and baseline measures of QOL and functional status were similar at sites with and without angiography. During hospitalization, patients treated at sites with angiography were more likely to undergo an invasive cardiac procedure than patients admitted at sites without angiography (angiography, 63% vs 26%; percutaneous transluminal coronary angioplasty, 33% vs 13%; and coronary artery bypass graft, 12% vs 5%). At 30 days and 6 months after AMI, QOL was slightly superior at sites with angiography, but by 1 year, most measures of QOL were back to baseline at both types of sites and were similar between the 2 groups. At 6 months, most standard health-related QOL components were similar; only physical and emotional role limitations were higher at sites with angiography. Return to work occurred earlier (at 30 days, 23% vs 12%), and a lower proportion of patients was readmitted for angina (within 1 year after AMI, 12% vs 18%) at sites with angiography. In the early post-AMI period, the QOL of patients admitted at sites with angiography was higher than that of patients admitted at sites without angiography. However, by 1 year, the QOL and functional status of patients was similar in both groups. Differences in QOL were greatest when differences in treatment were greatest, lending support to a positive albeit small association between an early invasive approach to post-AMI care and improved QOL.

  17. Regulation of leaf senescence and crop genetic improvement.

    PubMed

    Wu, Xiao-Yuan; Kuai, Ben-Ke; Jia, Ji-Zeng; Jing, Hai-Chun

    2012-12-01

    Leaf senescence can impact crop production by either changing photosynthesis duration, or by modifying the nutrient remobilization efficiency and harvest index. The doubling of the grain yield in major cereals in the last 50 years was primarily achieved through the extension of photosynthesis duration and the increase in crop biomass partitioning, two things that are intrinsically coupled with leaf senescence. In this review, we consider the functionality of a leaf as a function of leaf age, and divide a leaf's life into three phases: the functionality increasing phase at the early growth stage, the full functionality phase, and the senescence and functionality decreasing phase. A genetic framework is proposed to describe gene actions at various checkpoints to regulate leaf development and senescence. Four categories of genes contribute to crop production: those which regulate (I) the speed and transition of early leaf growth, (II) photosynthesis rate, (III) the onset and (IV) the progression of leaf senescence. Current advances in isolating and characterizing senescence regulatory genes are discussed in the leaf aging and crop production context. We argue that the breeding of crops with leaf senescence ideotypes should be an essential part of further crop genetic improvement. © 2012 Institute of Botany, Chinese Academy of Sciences.

  18. Generality of leaf trait relationships: A test across six biomes

    SciTech Connect

    Reich, P.B.; Ellsworth, D.S.; Walters, M.B.; Vose, J.M.; Gresham, C.; Volin, J.C.; Bowman, W.D. |

    1999-09-01

    Convergence in interspecific leaf trait relationships across diverse taxonomic groups and biomes would have important evolutionary and ecological implications. Such convergence has been hypothesized to result from trade-offs that limit the combination of plant traits for any species. Here the authors address this issue by testing for biome differences in the slope and intercept of interspecific relationships among leaf traits: longevity, net photosynthetic capacity (A{sub max}), leaf diffusive conductance (G{sub S}), specific leaf area (SLA), and nitrogen (N) status, for more than 100 species in six distinct biomes of the Americas. The six biomes were: alpine tundra-subalpine forest ecotone, cold temperate forest-prairie ecotone, montane cool temperate forest, desert shrubland, subtropical forest, and tropical rain forest. Despite large differences in climate and evolutionary history, in all biomes mass-based leaf N (N{sub mass}), SLA, G{sub S}, and A{sub max} were positively related to one another and decreased with increasing leaf life span. The relationships between pairs of leaf traits exhibited similar slopes among biomes, suggesting a predictable set of scaling relationships among key leaf morphological, chemical, and metabolic traits that are replicated globally among terrestrial ecosystems regardless of biome or vegetation type. However, the intercept (i.e., the overall elevation of regression lines) of relationships between pairs of leaf traits usually differed among biomes. With increasing aridity across sites, species had greater A{sub max} for a given level of G{sub S} and lower SLA for any given leaf life span. Using principal components analysis, most variation among species was explained by an axis related to mass-based leaf traits (A{sub max}, N, and SLA) while a second axis reflected climate, G{sub S}, and other area-based leaf traits.

  19. Leaf Phenology of Amazonian Canopy Trees as Revealed by Spectral and Physiochemical Measurements

    NASA Astrophysics Data System (ADS)

    Chavana-Bryant, C.; Gerard, F. F.; Malhi, Y.; Enquist, B. J.; Asner, G. P.

    2013-12-01

    The phenological dynamics of terrestrial ecosystems reflect the response of the Earth's biosphere to inter- and intra-annual dynamics of climatic and hydrological regimes. Some Dynamic Global Vegetation Models (GDVMs) have predicted that by 2050 the Amazon rainforest will begin to dieback (Cox et al. 2000, Nature) or that the ecosystem will become unsustainable (Salazar et al. 2007, GRL). One major component in DGVMs is the simulation of vegetation phenology, however, modelers are challenged with the estimation of tropical phenology which is highly complex. Current modeled phenology is based on observations of temperate vegetation and accurate representation of tropical phenology is long overdue. Remote sensing (RS) data are a key tool in monitoring vegetation dynamics at regional and global scales. Of the many RS techniques available, time-series analysis of vegetation indices (VIs) has become the most common approach in monitoring vegetation phenology (Samanta et al. 2010, GRL; Bradley et al. 2011, GCB). Our research focuses on investigating the influence that age related variation in the spectral reflectance and physiochemical properties of leaves may have on VIs of tropical canopies. In order to do this, we collected a unique leaf and canopy phenological dataset at two different Amazonian sites: Inselberg, French Guyana (FG) and Tambopata, Peru (PE). Hyperspectral reflectance measurements were collected from 4,102 individual leaves sampled to represent different leaf ages and vertical canopy positions (top, mid and low canopy) from 20 different canopy tree species (8 in FG and 12 in PE). These leaf spectra were complemented with 1) leaf physical measurements: fresh and dry weight, area and thickness, LMA and LWC and 2) leaf chemical measurements: %N, %C, %P, C:N and d13C. Canopy level observations included top-of-canopy reflectance measurements obtained using a multispectral 16-band radiometer, leaf demography (tot. number and age distribution) and branch

  20. A Journey Through a Leaf: Phenomics Analysis of Leaf Growth in Arabidopsis thaliana

    PubMed Central

    Vanhaeren, Hannes; Gonzalez, Nathalie; Inzé, Dirk

    2015-01-01

    In Arabidopsis, leaves contribute to the largest part of the aboveground biomass. In these organs, light is captured and converted into chemical energy, which plants use to grow and complete their life cycle. Leaves emerge as a small pool of cells at the vegetative shoot apical meristem and develop into planar, complex organs through different interconnected cellular events. Over the last decade, numerous phenotyping techniques have been developed to visualize and quantify leaf size and growth, leading to the identification of numerous genes that contribute to the final size of leaves. In this review, we will start at the Arabidopsis rosette level and gradually zoom in from a macroscopic view on leaf growth to a microscopic and molecular view. Along this journey, we describe different techniques that have been key to identify important events during leaf development and discuss approaches that will further help unraveling the complex cellular and molecular mechanisms that underlie leaf growth. PMID:26217168

  1. Leaf growth is conformal

    NASA Astrophysics Data System (ADS)

    Alim, Karen; Armon, Shahaf; Shraiman, Boris I.; Boudaoud, Arezki

    2016-10-01

    Growth pattern dynamics lie at the heart of morphogenesis. Here, we investigate the growth of plant leaves. We compute the conformal transformation that maps the contour of a leaf at a given stage onto the contour of the same leaf at a later stage. Based on the mapping we predict the local displacement field in the leaf blade and find it to agree with the experimentally measured displacement field to 92%. This approach is applicable to any two-dimensional system with locally isotropic growth, enabling the deduction of the whole growth field just from observation of the tissue contour.

  2. The generality of leaf size versus number trade-off in temperate woody species.

    PubMed

    Yang, Dongmei; Li, Guoyong; Sun, Shucun

    2008-10-01

    Trade-offs are fundamental to life-history theory, and the leaf size vs. number trade-off has recently been suggested to be of importance to our understanding leaf size evolution. The purpose of the present study was to test whether the isometric, negative relationship between leaf size and number found by Kleiman and Aarssen is conserved between plant functional types and between habitats. Leaf mass, area and number, and stem mass and volume of current-year shoots were measured for 107 temperate broadleaved woody species at two altitudes on Gongga Mountain, south-west China. The scaling relationships of leaf size (leaf area and mass) vs. (mass- and volume-based) leafing intensity were analysed in relation to leaf habit, leaf form and habitat type. Trait relationships were determined with both a standardized major axis method and a phylogenetically independent comparative method. Significant negative, isometric scaling relationships between leaf size and leafing intensity were found to be consistently conserved across species independent of leaf habit, leaf form and habitat type. In particular, about 99 % of the variation in leaf mass across species could be accounted for by proportional variation in mass-based leafing intensity. The negative correlations between leaf size and leafing intensity were also observed across correlated evolutionary divergences. However, evergreen species had a lower y-intercept in the scaling relationships of leaf area vs. leafing intensity than deciduous species. This indicated that leaf area was smaller in the evergreen species at a given leafing intensity than in the deciduous species. The compound-leaved deciduous species were observed usually to have significant upper shifts along the common slopes relative to the simple-leaved species, which suggested that the compound-leaved species were larger in leaf size but smaller in leafing intensity than their simple counterparts. No significant difference was found in the scaling

  3. Project LEAF Documents

    EPA Pesticide Factsheets

    Project LEAF has a goal of educating farmworkers about how to reduce pesticide exposure to their families from pesticide residues they may be inadvertently taking home on their clothing, etc. Find outreach materials.

  4. Leaf Phenological Characters of Main Tree Species in Urban Forest of Shenyang

    PubMed Central

    Xu, Sheng; Xu, Wenduo; Chen, Wei; He, Xingyuan; Huang, Yanqing; Wen, Hua

    2014-01-01

    Background Plant leaves, as the main photosynthetic organs and the high energy converters among primary producers in terrestrial ecosystems, have attracted significant research attention. Leaf lifespan is an adaptive characteristic formed by plants to obtain the maximum carbon in the long-term adaption process. It determines important functional and structural characteristics exhibited in the environmental adaptation of plants. However, the leaf lifespan and leaf characteristics of urban forests were not studied up to now. Methods By using statistic, linear regression methods and correlation analysis, leaf phenological characters of main tree species in urban forest of Shenyang were observed for five years to obtain the leafing phenology (including leafing start time, end time, and duration), defoliating phenology (including defoliation start time, end time, and duration), and the leaf lifespan of the main tree species. Moreover, the relationships between temperature and leafing phenology, defoliating phenology, and leaf lifespan were analyzed. Findings The timing of leafing differed greatly among species. The early leafing species would have relatively early end of leafing; the longer it took to the end of leafing would have a later time of completed leafing. The timing of defoliation among different species varied significantly, the early defoliation species would have relatively longer duration of defoliation. If the mean temperature rise for 1°C in spring, the time of leafing would experience 5 days earlier in spring. If the mean temperature decline for 1°C, the time of defoliation would experience 3 days delay in autumn. Interpretation There is significant correlation between leaf longevity and the time of leafing and defoliation. According to correlation analysis and regression analysis, there is significant correlation between temperature and leafing and defoliation phenology. Early leafing species would have a longer life span and consequently have

  5. [Influence of photosynthetic parameters on leaf longevity].

    PubMed

    Vasfilov, S P

    2015-01-01

    Higher plants show a wide range of leaf lifespan (LL) variability. LL is calculated as a sum of functional LL(f) (corresponding to the time of active photosynthesis and CO2 accumulation in the leaf) and nonfunctional LL(n) (the time of photosynthetic activity absence). For evergreen species of boreal zones, LL(n) corresponds to the period of winter rest. Photosynthetic potential of leaf (PPL), interpreted as the maximum possible amount of CO2 that can be fixed during its life, can be estimated on the basis of maximum photosynthesis rate (P(a)) dynamics during LL(f); the maximum (P(a max)) being achieved in mature leaf. Photosynthetic potential depends on LL(f) more strongly than on P(a max). The PPL/LL(f) ratio is indicative of the rate of PPL realization over leaf lifespan. As LL(f) shows strong positive correlation with LL, the latter parameter can also characterize the rate of PPL realization. Long LL(f) in evergreen species provides higher PPL, which is advantageous by comparison with deciduous ones. In evergreen species, the PPL itself is realized slower than in deciduous ones. The increase in LL(f) and LL is accompanied by the increase in leaf constructional cost (LCC(a)) as well as the decrease in photosynthesis rate. At that, photosynthesis rate per unit of dry weight (P(m)) decreases much faster than that per unit of leaf area (P(a)). Apparently, when considering dry leaf weight, the apoplast share seems to be much higher in long-living leaves of evergreen species than in short-living leaves of deciduous species. The leaf payback (LP) may be stabilized by unidirectional shifts in PPL and LCC(a). Species with short/long LL(f) and high/low PPL realization rate are typical for early/late succession stages and for habitats with the environmental conditions favorable/adverse for photosynthesis and growth. If the conditions for photosynthesis and growth are favorable, high PPL realization rate provides advantage in competition. The PPL realization rate is

  6. Leaf Senescence by Magnesium Deficiency

    PubMed Central

    Tanoi, Keitaro; Kobayashi, Natsuko I.

    2015-01-01

    Magnesium ions (Mg2+) are the second most abundant cations in living plant cells, and they are involved in various functions, including photosynthesis, enzyme catalysis, and nucleic acid synthesis. Low availability of Mg2+ in an agricultural field leads to a decrease in yield, which follows the appearance of Mg-deficient symptoms such as chlorosis, necrotic spots on the leaves, and droop. During the last decade, a variety of physiological and molecular responses to Mg2+ deficiency that potentially link to leaf senescence have been recognized, allowing us to reconsider the mechanisms of Mg2+ deficiency. This review focuses on the current knowledge about the physiological responses to Mg2+ deficiency including a decline in transpiration, accumulation of sugars and starch in source leaves, change in redox states, increased oxidative stress, metabolite alterations, and a decline in photosynthetic activity. In addition, we refer to the molecular responses that are thought to be related to leaf senescence. With these current data, we give an overview of leaf senescence induced by Mg deficiency. PMID:27135350

  7. This article has been retracted and is available online only: Exploration of Iranian intensive care nurses' experience of end-of-life care: a qualitative study.

    PubMed

    Albarran, John; Scholes, Julie

    2012-01-01

    RETRACTION: The following article from Nursing in Critical Care, 'Exploration of Iranian intensive care nurses' experience of end-of-life care: a qualitative study' by Sina Valiee, Reza Negarandeh and Nahid Dehghan Nayeri, published online on 9 May 2012 in Wiley Online Library (wileyonlinelibrary.com), has been retracted by agreement between the authors and the journal Editors. The retraction has been agreed due to errors in the manuscript handling process which meant that an early version of the article was published that did not include all the amendments made as part of the peer review process. John Albarran and Julie Scholes Editors Nursing in Critical Care REFERENCE Valiee, S., Negarandeh, R. and Dehghan Nayeri, N. (2012), Exploration of Iranian intensive care nurses' experience of end-of-life care: a qualitative study. Nursing in Critical Care. doi: 10.1111/j.1478-5153.2012.00505.x.

  8. Bud composition, branching patterns and leaf phenology in cerrado woody species.

    PubMed

    Damascos, M A; Prado, C H B A; Ronquim, C C

    2005-11-01

    Plants have complex mechanisms of aerial biomass exposition, which depend on bud composition, the period of the year in which shoot extension occurs, branching pattern, foliage persistence, herbivory and environmental conditions. The influence of water availability and temperature on shoot growth, the bud composition, the leaf phenology, and the relationship between partial leaf fall and branching were evaluated over 3 years in Cerrado woody species Bauhinia rufa (BR), Leandra lacunosa (LL) and Miconia albicans (MA). Deciduous BR preformed organs in buds and leaves flush synchronously at the transition from the dry to the wet season. The expansion time of leaves is <1 month. Main shoots (first-order axis, A1 shoots) extended over 30 d and they did not branch. BR budding and foliage unfolds were brought about independently of inter-annual rainfall variations. By contrast, in LL and MA evergreen species, the shoot extension rate and the neoformation of aerial organs depended on rainfall. Leaf emergence was continuous for 2-6 months and lamina expansion took place over 1-4 months. The leaf life span was 5-20 months and the main A1 shoot extension happened over 122-177 d. Both evergreen species allocated biomass to shoots, leaves or flowers continuously during the year, branching in the middle of the wet season to form second-order (A2 shoots) and third-order (A3 shoots) axis in LL and A2 shoots in MA. Partial shed of A1 shoot leaves would facilitate a higher branching intensity A2 shoot production in LL than in MA. MA presented a longer leaf life span, produced a lower percentage of A2 shoots but had a higher meristem persistence on A1 and A2 shoots than LL. It was possible to identify different patterns of aerial growth in Cerrado woody species defined by shoot-linked traits such as branching pattern, bud composition, meristem persistence and leaf phenology. These related traits must be considered over and above leaf deciduousness for searching functional guilds in a

  9. Bud Composition, Branching Patterns and Leaf Phenology in Cerrado Woody Species

    PubMed Central

    DAMASCOS, M. A.; PRADO, C. H. B. A.; RONQUIM, C. C.

    2005-01-01

    • Background and Aims Plants have complex mechanisms of aerial biomass exposition, which depend on bud composition, the period of the year in which shoot extension occurs, branching pattern, foliage persistence, herbivory and environmental conditions. • Methods The influence of water availability and temperature on shoot growth, the bud composition, the leaf phenology, and the relationship between partial leaf fall and branching were evaluated over 3 years in Cerrado woody species Bauhinia rufa (BR), Leandra lacunosa (LL) and Miconia albicans (MA). • Key Results Deciduous BR preformed organs in buds and leaves flush synchronously at the transition from the dry to the wet season. The expansion time of leaves is <1 month. Main shoots (first-order axis, A1 shoots) extended over 30 d and they did not branch. BR budding and foliage unfolds were brought about independently of inter-annual rainfall variations. By contrast, in LL and MA evergreen species, the shoot extension rate and the neoformation of aerial organs depended on rainfall. Leaf emergence was continuous for 2–6 months and lamina expansion took place over 1–4 months. The leaf life span was 5–20 months and the main A1 shoot extension happened over 122–177 d. Both evergreen species allocated biomass to shoots, leaves or flowers continuously during the year, branching in the middle of the wet season to form second-order (A2 shoots) and third-order (A3 shoots) axis in LL and A2 shoots in MA. Partial shed of A1 shoot leaves would facilitate a higher branching intensity A2 shoot production in LL than in MA. MA presented a longer leaf life span, produced a lower percentage of A2 shoots but had a higher meristem persistence on A1 and A2 shoots than LL. • Conclusions It was possible to identify different patterns of aerial growth in Cerrado woody species defined by shoot-linked traits such as branching pattern, bud composition, meristem persistence and leaf phenology. These related traits must be

  10. Speculations on the origin of life and thermophily: Review of available information on reverse gyrase suggests that hyperthermophilic procaryotes are not so primitive

    NASA Astrophysics Data System (ADS)

    Forterre, Patrick; Confalonier, Fabrice; Charbonnier, Franck; Duguet, Michel

    1995-06-01

    All present-day hyperthermophiles studied so far (eitherBacteria orArchaea) contain a unique DNA topoisomerase, reverse gyrase, which probably helps to stabilize genomic DNA at high temperature. Herein the data relating this enzyme is reviewed and discussed from the perspective of the nature of the last detectable common ancestor and the origin of life. The sequence of the gene encoding reverse gyrase from an archaeon,Sulfolobus acidocaldarius, suggests that this enzyme contains both a helicase and a topoisomerase domains (Confalonieriet al.,Proc. Natl. Acad. Sci., 1993, 90, 4735). Accordingly, it has been proposed that reverse gyrase originated by the fusion of DNA helicase and DNA topoisomerase genes. If reverse gyrase is essential for life at high temperature, its composite structure suggests that DNA helicases and topoisomerases appeared independently and first evolved in a mesophilic world. Such scenario contradicts the hypothesis that a direct link connects present day hyperthermophiles to a hot origin of life. We discuss different patterns for the early cellular evolution in which reverse gyrase appeared either before the emergence of the last common ancestor ofArchaea, Bacteria andEucarya, or in a lineage common to the two procaryotic domains. The latter scenario could explain why all today hyperthermophiles are procaryotes.

  11. Deer predation on leaf miners via leaf abscission

    NASA Astrophysics Data System (ADS)

    Yamazaki, Kazuo; Sugiura, Shinji

    2008-03-01

    The evergreen oak Quercus gilva Blume sheds leaves containing mines of the leaf miner Stigmella sp. (Lepidoptera: Nepticulidae) earlier than leaves with no mines in early spring in Nara, central Japan. The eclosion rates of the leaf miner in abscised and retained leaves were compared in the laboratory to clarify the effects of leaf abscission on leaf miner survival in the absence of deer. The leaf miner eclosed successfully from both fallen leaves and leaves retained on trees. However, sika deer ( Cervus nippon centralis Kishida) feed on the fallen mined leaves. Field observations showed that deer consume many fallen leaves under Q. gilva trees, suggesting considerable mortality of leaf miners due to deer predation via leaf abscission. This is a previously unreported relationship between a leaf miner and a mammalian herbivore via leaf abscission.

  12. Deer predation on leaf miners via leaf abscission.

    PubMed

    Yamazaki, Kazuo; Sugiura, Shinji

    2008-03-01

    The evergreen oak Quercus gilva Blume sheds leaves containing mines of the leaf miner Stigmella sp. (Lepidoptera: Nepticulidae) earlier than leaves with no mines in early spring in Nara, central Japan. The eclosion rates of the leaf miner in abscised and retained leaves were compared in the laboratory to clarify the effects of leaf abscission on leaf miner survival in the absence of deer. The leaf miner eclosed successfully from both fallen leaves and leaves retained on trees. However, sika deer (Cervus nippon centralis Kishida) feed on the fallen mined leaves. Field observations showed that deer consume many fallen leaves under Q. gilva trees, suggesting considerable mortality of leaf miners due to deer predation via leaf abscission. This is a previously unreported relationship between a leaf miner and a mammalian herbivore via leaf abscission.

  13. Impact of plant architecture versus leaf quality on attack by leaf-tying caterpillars on five oak species.

    PubMed

    Marquis, Robert J; Lill, John T

    2010-05-01

    Because shelter-building herbivorous insect species often consider structural features of their host plants in selecting construction sites, their probability of attack is likely to be a function of some combination of plant architectural traits and leaf quality factors. We tested the hypothesis that plant architecture, in the form of the number of touching leaves, influences interspecific variation in attack by leaf-tying caterpillars in five species of sympatric Missouri oaks (Quercus). We compared colonization on control branches, in which both architecture and leaf quality were potentially important, with colonization on experimental branches for which we controlled for the effects of architecture by creating equal numbers of artificial ties. Colonization of artificial ties was highly correlated with natural colonization on neighboring control branches, suggesting that leaf quality factors and not architecture influenced interspecific variation in attack by leaf-tying caterpillars. Of the leaf quality factors measured (water, protein-binding capacity, nitrogen, specific leaf area, pubescence, and toughness), nitrogen was the most explanatory. With the exception of white oak, natural leaf tie colonization was positively correlated with nitrogen availability (ratio of nitrogen to protein-binding capacity), and negatively correlated with protein-binding capacity of leaf extracts. Both host plant species and subgenus oak influenced the community composition of leaf-tying caterpillars and the non-tying symbionts colonizing the ties. Host plant differences in leaf nitrogen content were positively correlated with pupal weight of one of two caterpillar species reared on all five host plant species. Thus, interspecific differences in nitrogen, nitrogen availability, and protein-binding capacity of leaf extracts are the best predictors at this time of interspecific differences in attack by leaf-tying caterpillars, in turn affecting their success on individual host plants

  14. [Not Available].

    PubMed

    Trochu, Jean-Noël

    2014-10-01

    The World Health Organization defines Quality of life (QOL) as an individual's perception of their position in lfe in the context of the culture and value systems in which they live and in relation to their goals, expectations, standards and concerns. During chronic heart failure several factors contribute to the alteration of QOL: congestion, dyspnea, fatigue, sleep disturbances, anxiety, depression, side effects of medications, impacts on personal life and disruption of social interactions which can modify patients' social roles, life situation and ability to travel. NYHA class, exercise tolerance represent physician-reported patient well-being parameters but do not actually assess alterations expressed by the patient. There are several specific instruments to better evaluate QOL: they can be generic (self-assessment of general well-being), health related QOL (SF36), specific to diseases (Minnesota Living With Heart Failure Questionnaire) or domain specific (anxiety, depression). Impact of ACE inhibitors, angiotensin 2 antagonists, and beta-blockers are small while that of cardiac resynchronization and multidisciplinary management programmes are more efficient. In advanced heart failure when patient recognize equal importance between improvement in QOL and gain in survival, left ventricle assist devices (LVAD) significantly improve QOL at early (3 months) and long-term (2 years) follow up. LVADs allow the rapid return of the patients at home and genuine autonomy in the context of a personalized care plan supervised by the referring centre. Beneficial effects are close to those of heart transplantation but still are limited by the need of taking care of their equipment.

  15. [Not Available].

    PubMed

    Todorova, M; Triphonov, I

    The authors are investigated the life and all activity of the man of note since the time of Bulgarian National Renaissance. He graduate Medical Faculty in Bucurest and establish contacts with g.s. Rakovsky, Vasil Levsky and others Bulgarian revolutionary. After his back in Bulgaria he was physician in the town Stara Zagora and Sliven. N. Planinsky, bishop Seraphim, D-r Geogry Mirovich and other create the first society of the Red Cross. With co-operation of P.R. Slaveikov, publish the first Bulgarian newspaper in Sliven "Bulgarian flag". His public activity was illuminate as like as people "representative and functionary of the United".

  16. Morphogenesis of simple leaves: regulation of leaf size and shape.

    PubMed

    Rodriguez, Ramiro E; Debernardi, Juan M; Palatnik, Javier F

    2014-01-01

    Plants produce new organs throughout their life span. Leaves first initiate as rod-like structures protruding from the shoot apical meristem, while they need to pass through different developmental stages to become the flat organ specialized in photosynthesis. Leaf morphogenesis is an active process regulated by many genes and pathways that can generate organs with a wide variety of sizes and shapes. Important differences in leaf architecture can be seen among different species, but also in single individuals. A key aspect of leaf morphogenesis is the precise control of cell proliferation. Modification or manipulation of this process may lead to leaves with different sizes and shapes, and changes in the organ margins and curvature. Many genes required for leaf development have been identified in Arabidopsis thaliana, and the mechanisms underlying leaf morphogenesis are starting to be unraveled at the molecular level. © 2013 Wiley Periodicals, Inc.

  17. Apparent Overinvestment in Leaf Venation Relaxes Leaf Morphological Constraints on Photosynthesis in Arid Habitats1[OPEN

    PubMed Central

    de Boer, Hugo J.; Drake, Paul L.; Wendt, Erin; Price, Charles A.; Schulze, Ernst-Detlef; Turner, Neil C.; Nicolle, Dean

    2016-01-01

    Leaf veins supply the mesophyll with water that evaporates when stomata are open to allow CO2 uptake for photosynthesis. Theoretical analyses suggest that water is optimally distributed in the mesophyll when the lateral distance between veins (dx) is equal to the distance from these veins to the epidermis (dy), expressed as dx:dy ≈ 1. Although this theory is supported by observations of many derived angiosperms, we hypothesize that plants in arid environments may reduce dx:dy below unity owing to climate-specific functional adaptations of increased leaf thickness and increased vein density. To test our hypothesis, we assembled leaf hydraulic, morphological, and photosynthetic traits of 68 species from the Eucalyptus and Corymbia genera (termed eucalypts) along an aridity gradient in southwestern Australia. We inferred the potential gas-exchange advantage of reducing dx beyond dy using a model that links leaf morphology and hydraulics to photosynthesis. Our observations reveal that eucalypts in arid environments have thick amphistomatous leaves with high vein densities, resulting in dx:dy ratios that range from 1.6 to 0.15 along the aridity gradient. Our model suggests that, as leaves become thicker, the effect of reducing dx beyond dy is to offset the reduction in leaf gas exchange that would result from maintaining dx:dy at unity. This apparent overinvestment in leaf venation may be explained from the selective pressure of aridity, under which traits associated with long leaf life span, high hydraulic and thermal capacitances, and high potential rates of leaf water transport confer a competitive advantage. PMID:27784769

  18. [Not Available].

    PubMed

    Cederholm, Tommy; Hellénius, Mai-Lis

    2016-06-02

    By the food intake man is daily exposed to numerous chemical agents with impact on ageing and longevity. Over the last two centuries longevity in the affluent societies has increased by 2 years per decade. Improved food habits are important contributing factors.  Dietary patterns of populations with long life-spans, like the traditional Mediterranean diet and the Okinawa Island diet, provide the basis to recommend plant foods like vegetables, legumes, fruits, non-tropical vegetable oils as basic fat, light meat (e.g. poultry) of moderate amounts, plenty of fish and moderate beverage intakes of wine, coffee and tea. Oxidative damage is suggested as one major reason for exaggerated ageing. Foods that promote longevity are rich in antioxidants. Still there is no evidence that extra anti-oxidant supplementation has any beneficial effects. Energy balance to avoid obesity at young and middle ages, e.g. by calorie restricted diets and increased physical activity, promotes longevity, whereas at older age overweight is usually associated with a longer life-span.

  19. [Not Available].

    PubMed

    Fakhoury, May; Jacqz-Aigrain, Evelyne; de Beaumais, Tiphaine; Médard, Yves

    2010-01-01

    6-mercaptopurine, a key drug for the treatment of acute lymphoblastic leukaemia in children, is a prodrug metabolized into 6-thioguanine (6-TGN) which are the active compounds and into methylated metabolites, primary by thiopurine S-methyltransferase enzyme (TPMT). This enzyme displays important inter subject variability linked to a genetic polymorphism: when treated with standard doses of thiopurine, TPMT-deficient and heterozygous patients are at great risk for developing severe and potentially life-threatening toxicity (hematopoietic, hepatic, mucositis. . . ) but show a better survival rate while patients with high TPMT activity (wild type) present lower peripheral red blood cells 6-TGN concentrations and a higher risk of leukemia relapse. Genotyping remains crucial before 6-MP administration at diagnosis to identify patients with homozygous mutant TPMT genotype and therefore prevent severe and life-threatening toxicity, and to individualize therapy according to TMPT genotype. Follow-up of ALL treatment should preferentially be based on repeated determinations of intracellular active metabolites (6-thioguanine nucleotides) and methylated metabolites in addition to haematological surveillance.

  20. Damped leaf flexure hinge

    NASA Astrophysics Data System (ADS)

    Chen, Zhong; Chen, Guisheng; Zhang, Xianmin

    2015-05-01

    Flexure-based mechanism like compliant actuation system embeds complex dynamics that will reduce the control bandwidth and limits their dynamic positioning precision. This paper presents a theoretical model of a leaf flexure hinge with damping layers using strain energy method and Kelvin damping model. The modified loss factor of the damped leaf flexure hinge is derived, and the equivalent viscous damping coefficient of the damped leaf hinge is obtained, which could be used to improve the pseudo-rigid-model. The free vibration signals of the hinge in three different damping configurations are measured. The experimental modal analysis also is performed on the three kinds of damped leaf flexure hinges in order to evaluate their 1st order bending natural frequency and vibration-suppressing effects. The evaluation of modified loss factor model also is performed. The experimental results indicate that the constrained layer damping can enhance the structure damping of the hinge even if only single damping layer each side, the modified loss factor model can get good predicts of a damped leaf flexure hinge in the frequency range below 1st order natural frequency, and it is necessary that the dimensional parameters of the damping layers and basic layer of the hinge should be optimized for simplification at the mechanism's design stage.

  1. Damped leaf flexure hinge.

    PubMed

    Chen, Zhong; Chen, Guisheng; Zhang, Xianmin

    2015-05-01

    Flexure-based mechanism like compliant actuation system embeds complex dynamics that will reduce the control bandwidth and limits their dynamic positioning precision. This paper presents a theoretical model of a leaf flexure hinge with damping layers using strain energy method and Kelvin damping model. The modified loss factor of the damped leaf flexure hinge is derived, and the equivalent viscous damping coefficient of the damped leaf hinge is obtained, which could be used to improve the pseudo-rigid-model. The free vibration signals of the hinge in three different damping configurations are measured. The experimental modal analysis also is performed on the three kinds of damped leaf flexure hinges in order to evaluate their 1st order bending natural frequency and vibration-suppressing effects. The evaluation of modified loss factor model also is performed. The experimental results indicate that the constrained layer damping can enhance the structure damping of the hinge even if only single damping layer each side, the modified loss factor model can get good predicts of a damped leaf flexure hinge in the frequency range below 1st order natural frequency, and it is necessary that the dimensional parameters of the damping layers and basic layer of the hinge should be optimized for simplification at the mechanism's design stage.

  2. Rapid, high-resolution measurement of leaf area and leaf orientation using terrestrial LiDAR scanning data

    NASA Astrophysics Data System (ADS)

    Bailey, Brian N.; Mahaffee, Walter F.

    2017-06-01

    The rapid evolution of high performance computing technology has allowed for the development of extremely detailed models of the urban and natural environment. Although models can now represent sub-meter-scale variability in environmental geometry, model users are often unable to specify the geometry of real domains at this scale given available measurements. An emerging technology in this field has been the use of terrestrial LiDAR scanning data to rapidly measure the three-dimensional geometry of trees, such as the distribution of leaf area. However, current LiDAR methods suffer from the limitation that they require detailed knowledge of leaf orientation in order to translate projected leaf area into actual leaf area. Common methods for measuring leaf orientation are often tedious or inaccurate, which places constraints on the LiDAR measurement technique. This work presents a new method to simultaneously measure leaf orientation and leaf area within an arbitrarily defined volume using terrestrial LiDAR data. The novelty of the method lies in the direct measurement of the fraction of projected leaf area G from the LiDAR data which is required to relate projected leaf area to total leaf area, and in the new way in which radiation transfer theory is used to calculate leaf area from the LiDAR data. The method was validated by comparing LiDAR-measured leaf area to (1) ‘synthetic’ or computer-generated LiDAR data where the exact area was known, and (2) direct measurements of leaf area in the field using destructive sampling. Overall, agreement between the LiDAR and reference measurements was very good, showing a normalized root-mean-squared-error of about 15% for the synthetic tests, and 13% in the field.

  3. [Not Available].

    PubMed

    Shingarov, G H

    1970-01-01

    In this paper some of the philosophical problems of the history of neurophysiology are discussed, paying special attention to the credit going to Hegel, Rene Decart, to the Russian materialistic school, led by I. P. Pavlov and others. Of particular interest is the interpretation of the following problems: the historical consistency of the appearance of the basic conceptions with which the pre-Pavlov neurophysiology was chiefly concerned, the logical subordination of its categories and ideas, the creation of the basic concepts in the study of the higher nervous activity by I. P. Pavlov, their logical and practical substantiation and the like. An attempt is made, proceeding from dialectic materialism positions, for interpretation of the problems posed, which are of paramount theoretic and practical importance for science and life.

  4. [Not Available].

    PubMed

    Pecevski, Dejan; Natschläger, Thomas; Schuch, Klaus

    2009-01-01

    The Parallel Circuit SIMulator (PCSIM) is a software package for simulation of neural circuits. It is primarily designed for distributed simulation of large scale networks of spiking point neurons. Although its computational core is written in C++, PCSIM's primary interface is implemented in the Python programming language, which is a powerful programming environment and allows the user to easily integrate the neural circuit simulator with data analysis and visualization tools to manage the full neural modeling life cycle. The main focus of this paper is to describe PCSIM's full integration into Python and the benefits thereof. In particular we will investigate how the automatically generated bidirectional interface and PCSIM's object-oriented modular framework enable the user to adopt a hybrid modeling approach: using and extending PCSIM's functionality either employing pure Python or C++ and thus combining the advantages of both worlds. Furthermore, we describe several supplementary PCSIM packages written in pure Python and tailored towards setting up and analyzing neural simulations.

  5. [Not Available].

    PubMed

    Perrotta, F M; Lubrano, E

    2016-09-09

    Psoriatic arthritis (PsA) is a chronic inflammatory disease that possibly leads to structural damage and to a reduction of joint function and poor quality of life. Treatment of PsA has changed since its introduction of anti- TNF drugs, which have shown to reduce the symptoms and signs of the disease and slow the radiographic progression. However, recently, the discovery of new pathogenic mechanisms have made possible the development of new molecules that target pro-inflammatory cytokines involved in skin, joint and entheseal inflammation. New drugs like ustekinumab, secukinumab and apremilast inhibit interleukin axis and intracellular pathways and showed their efficacy and safety in randomized clinical trials. These drugs have been recently approved for the treatment of PsA and included in the new EULAR and GRAPPA treatment recommendations. The aim of this paper is to briefly review the clinical trials that led to their approval for PsA.

  6. [Not Available].

    PubMed

    Debruyne, Danièle; Pailliet-Loilier, Magalie; Lelong-Boulouard, Véronique; Coquerel, Antoine; Bentué-Ferrer, Danièle

    2010-01-01

    Clonazepam is a 1-4 benzodiazepine mainly used to treat epilepsy and epileptiform convulsion state. Rapidly absorbed after oral administration, it is widely distributed in the organism and is extensively converted in metabolites, poorly or not active, eliminated mainly in urine (70%) and feces. Elimination half-life is long, around 40 h. In adult and child, several studies showed a concentration-effect relation. Meanwhile, a large inter-individual variability in the dose-concentration relation was observed. A 15-50 μg/L range of clonazepam blood concentrations appears to be retained as an acceptable target to control a majority of epileptic seizures. The Therapeutic Drug Monitoring (TDM) of clonazepam can be considered as possibly useful in case of association with CYP450 inducers or inhibitors, suspicion of poor observance, or toxicity signs.

  7. [Not Available].

    PubMed

    1992-03-25

    Archersstar Sudha Bhuchar, right, launches a video on breast screening for women from ethnic minorities, sponsored by the NHS. The video is available in six languages. Ms Bhuchar is pictured with programme co-ordinator Julietta Patrick.

  8. End-of-Life and Palliative Care for People with Intellectual Disabilities Who Have Cancer or Other Life-Limiting Illness: A Review of the Literature and Available Resources

    ERIC Educational Resources Information Center

    Tuffrey-Wijne, Irene; Hogg, James; Curfs, Leopold

    2007-01-01

    Background: As patterns of morbidity and mortality are changing, more people with intellectual disabilities develop cancer or other life-limiting illness. This paper reviews the literature around the need of people with intellectual disabilities for palliative care. Methods: A range of databases and the World Wide Web were searched for relevant…

  9. [Not Available].

    PubMed

    Jacqueline, Sophie; Bleton, Jean; Huynh-Charlier, Isabelle; Minchin, Sébastien; Muller, Anne-Laure; Poupon, Joël; Charlier, Philippe

    2016-01-01

    Today, the development of analytic methods brings new scientific insights into the research on the mummification process used by embalmers in ancient Egypt. The application of these techniques of molecular analysis, elementary analysis, botanical analysis and bibliographic analysis of ancient texts allows us to know the composition of mummification balms and material involved in the conservation of the body. Such substances, which are mineral, animal or plant material, played a practical and a symbolic part in the composition of balms used for the preservation of mummified bodies and therefore in the passage to the eternal life after the death. The comparison of analysis results can inform us about changes in embalming techniques depending of the time, the place of mummification, the deceased's social status. However the number of mummies studied is very small compared to the number of bodies that were mummified. Finally the techniques of mummification and making balms were very variable according to practitioners and their modus operandi. Today, using these technic of chemical analysis and medical imaging techniques, we can authenticate and reconstruct the history of museum pieces, as we have done in the unpublished studies conducted in support of literature data previously collected.

  10. [Not Available].

    PubMed

    Meszaros, J

    1999-01-01

    By the end of World War I the Hungarian Psychoanalytic movement was strong and deeply integrated into the cultural and intellectual life of Budapest. The city was ready to be the center of the European psychoanalysis. The paper discusses how Budapest lost its growing eminence as a center, but because of the political-social changes in Hungary in the years 1918-1920. The paper will examine the two waves of Hungarian emigration between the world wars, the first in the early twenties to the Weimar Republic, and then in the thirties, to the United States and Australia. These movements of important Hungarian psychoanalysts, account both becoming weaker of the Budapest School and at the same time its influence in other countries. The author highlights the outstanding role of the American Psychoanalytic Association's setting up the Emergency Committee on Relief and Immigration in saving the lives of many European colleagues. America was open to European psychoanalysis at that time and in return immigrants facilitated the development of modern psychotherapy and psychoanalysis. The influence of Vienna, Budapest and Berlin can be traced in contemporary psychoanalytic culture in the United States. The documentation for this paper was researched in Washington, D.C., New York and London, supported by fellowships and grants from the Woodrow Wilson International Center and the Soros Foundation.

  11. Comparative leaf development in angiosperms.

    PubMed

    Tsukaya, Hirokazu

    2014-02-01

    Recent accumulation of our knowledge on basic leaf development mechanisms in model angiosperm species has allowed us to pursue evolutionary development (evo/devo) studies of various kinds of leaf development. As a result, unexpected findings and clues have been unearthed aiding our understanding of the mechanisms involved in the diversity of leaf morphology, although the covered remain limited. In this review, we highlight recent findings of diversified leaf development in angiosperms.

  12. Maple Leaf Outdoor Centre.

    ERIC Educational Resources Information Center

    Maguire, Molly; Gunton, Ric

    2000-01-01

    Maple Leaf Outdoor Centre (Ontario) has added year-round outdoor education facilities and programs to help support its summer camp for disadvantaged children. Schools, youth centers, religious groups, and athletic teams conduct their own programs, collaborate with staff, or use staff-developed programs emphasizing adventure education and personal…

  13. Bacterial leaf spot

    USDA-ARS?s Scientific Manuscript database

    Bacterial leaf spot has been reported in Australia (Queensland), Egypt, El Salvador, India, Japan, Nicaragua, Sudan, and the United States (Florida, Iowa, Kansas, Maryland, and Wisconsin). It occasionally causes locally severe defoliation and post-emergence damping-off and stunting. The disease is...

  14. Cucumber leaf spot virus

    USDA-ARS?s Scientific Manuscript database

    Cucumber leaf spot virus (CLSV) was originally identified from cucumber (Cucumis sativus) in Germany, but has since been found in various parts of Europe, the UK, and the Middle East, including Jordan, Saudi Arabia, Bulgaria, Poland, and Spain. CLSV is known to cause symptoms ranging from chloroti...

  15. [Not Available].

    PubMed

    Fadare, Jo; Obimakinde, Am; Olaogun, Do; Afolayan, Jm; Olatunya, O; Ogundipe, Ko

    2014-09-01

    Nurses play a major role all over the world in the palliative care team. The aim of this study was to investigate the knowledge and attitude of nurses toward palliative care in a tertiary level hospital in Nigeria. This cross-sectional questionnaire-based study was carried out among nurses at a tertiary health care facility in Ado-Ekiti, South-West Nigeria. A cross-sectional questionnaire-based study was carried out. The questionnaire sought information about the sociodemographic profile of respondents, their knowledge of definition and philosophy of palliative care among other things. Descriptive statistics was used to obtain the general characteristics of the study participants, while Chi-square was used to determine the association between categorical variables. A two-sided P < 0.05 was considered as significant. A total of 100 questionnaires were returned with a female preponderance among the respondents with F: M ratio of 9:1. Regarding the definition of palliative care, 71.8% (48/66) of the respondents understood palliative care to be about pain medicine, 55% (33/60) thought it to be geriatric medicine, while 90.2% (83/92) felt palliative care is about the active care of the dying. Exactly 80.5% (66/82) respondents agreed that palliative care recognizes dying as a normal process while 84.1% (74/88) respondents were of the opinion that all dying patients would require palliative care. The use of morphine would improve the quality of life of patients according to 68.9% (42/61) of respondents. There are gaps in the knowledge of healthcare workers in the area of palliative care and this call for a review of the current nursing curriculum and practice guidelines in Nigeria.

  16. BOREAS TE-9 NSA Leaf Chlorophyll Density

    NASA Technical Reports Server (NTRS)

    Hall, Forrest G. (Editor); Curd, Shelaine (Editor); Margolis, Hank; Sy, Mikailou

    2000-01-01

    The BOREAS TE-9 team collected several data sets related to chemical and photosynthetic properties of leaves in boreal forest tree species. These data were collected to help provide an explanation of potential seasonal and spatial changes of leaf pigment properties in boreal forest species at the NSA. At different dates (FFC-Winter, FFC-Thaw, IFC-1, IFC-2, and IMC-3), foliage samples were collected from the upper third of the canopy for five NSA sites (YJP, OJP, OBS, UBS, and OA) near Thompson, Manitoba. Subsamples of 100 needles for black spruce, 20 needles for jack pine, and single leaf for trembling aspen were cut into pieces and immersed in a 20-mL DMF aliquot in a Nalgene test tube. The extracted foliage materials were then oven-dried at 68 C for 48 hours and weighed. Extracted leaf dry weight was converted to a total leaf area basis to express the chlorophyll content in mg/sq cm of total leaf area. The data are provided in tabular ASCII files. The data files are available on a CD-ROM (see document number 20010000884), or from the Oak Ridge National Laboratory (ORNL) Distributed Active Archive Center (DAAC).

  17. Availability and the use of work-life balance benefits guaranteed by the Polish Labour Code among workers employed on the basis of employment contracts in small and medium enterprises.

    PubMed

    Andysz, Aleksandra; Jacukowicz, Aleksandra; Stańczak, Aleksander; Drabek, Marcin

    2016-01-01

    Polish Labour Code provides employees with a range of solutions (benefits) supporting them in achieving balance between work and private life. This paper was aimed at indicating availability and the use of legal benefits supporting work-life balance (WLB) among Polish workers of small and medium enterprises. The study sample included 219 respondents, aged 22-64, working in small and medium enterprises and employed on the basis of employment contracts for at least a year. The respondents completed a questionnaire on availability and the use of benefits guaranteed by the Polish Labour Code, referring to their current workplaces. Most frequently the studied employees took sick leave because of one's own illness and leave on demand. In our sample, 45% of the women took maternity leave and 26% of the men took paternity leave. The respondents took educational and parental leave the least frequently. More than half of the respondents (58%) did not return to the same position after leave devoted to childcare, even though they had such a possibility. In fact, most of work-life balance benefits guaranteed by law were available to the employees of small and medium enterprises, regardless of their gender. Availability and the use of the majority of benefits were similar among the women and men. Availability of benefits depended on the specificity of industry and a profession, thus, future research on work-life balance policy should control for variables related to the character of work. This work is available in Open Access model and licensed under a CC BY-NC 3.0 PL license.

  18. Health plans--enforcement of right to reimbursement not available under ERISA section 502(a)(3). Great-West Life & Annuity Insurance Company v. Knudson.

    PubMed

    2003-01-01

    The United States Supreme Court reaffirmed its reluctance "to tamper with [the] enforcement scheme" embodied in ERISA by authorizing remedies not specifically authorized by ERISA's text, and held that section 502(c)(3) does not authorize a plan to bring an action to enforce the plan's reimbursement provisions because recovering monetary damages for reimbursement is not relief typically available in equity and, therefore, is not "other equitable relief" within the meaning of section 502(a)(3). An action to impose personal liability on the Knudsons for a contractual obligation to pay money is an action seeking legal, not equitable, relief and is not authorized by section 502(a)(3).

  19. [Not Available].

    PubMed

    Chevreuil, Claire; Polard, Elisabeth; Lemonnier, Eric; Guillemot, Paul; Bentué-Ferrer, Danièle

    2011-01-01

    Aripiprazole inaugurates a new generation of antipsychotics called dopamine-serotonin system stabilizers. Its mechanism of action is different as aripiprazole is a partial dopamine D2 and serotonin 5-HT1A receptor agonist and 5-HT2A receptor antagonist. Therefore, aripiprazole is thought to have an antagonistic action in the mesolimbic pathway but an agonistic action in the mesocortical pathway, tending to normalize the dopaminergic transmission regardless of the type of imbalance. Clinical trials involving children and adolescents have demonstrated the efficacy of aripiprazole in bipolar disorders, schizophrenia, mood disorders associated with pervasive developmental disorders, in tics and Tourette's. The most frequent side effects are extrapyramidal symptoms and sleepiness and are dose-dependant. Nevertheless, contrary to other second-generation antipsychotics available in France, it induces little weight gain, does not modify lipid and glucidic profiles, does not increase prolactin levels, or induce QTc lengthening. The main advantage of aripiprazole is its good safety profile, with different toxicity targets to other secondgeneration antipsychotics available in France. Aripiprazole appears to be an alternative for children and adolescents who are vulnerable to these side effects and are having trouble coping with them.

  20. Optimal leaf water use drives ecosystem water and carbon fluxes in a changing environment

    USDA-ARS?s Scientific Manuscript database

    Canopy water and carbon exchange rates are controlled by leaf-level adjustment of stomatal aperture and photosynthetic capacity. Both leaf-level stomatal conductance and the leaf photosynthetic machinery respond nonlinearly to soil water availability, atmospheric CO2 concentration, and other environ...

  1. [Not Available].

    PubMed

    Spivak, M

    1987-01-01

    of human physiology for instance. Huge amounts of energy and money were spent on realizing this theory: politicians, educators, the military, religious authorities, men of distinction, all fought for the best possible application of this miraculous principle which was believed to cure all ills in this world. Was it really worthwhile? Was it possible to expect objectively measurable results on a national scale if the social factors - such as standards of living, hygiene, working hours, urban conditions - were not taken into account? The history of this element requires a deep understanding of the evolution of most of the factors which make up real life in a country such as France, which experienced various stages in a industrial revolution as well as many political changes. In spite of this evolution, one must acknowledge that false beliefs survived well into the 1940s, and furthermore, physical exercise, whatever its form, still belongs in many ways to hedonism and is therefore difficult to impose as a universal solution to political problems. As a democracy, France could not accept militarization.

  2. [Not Available].

    PubMed

    Blanchard, Elodie; de Lara, Manuel Tunon

    2013-01-01

    Pholcodine is an opioid that has been widely used worldwide since 1950 for the treatment of non-productive cough in children and adults. The results of early preclinical studies but also those of recent clinical trials have shown the antitussive efficacy of pholcodine to be superior to that of codeine, of longer duration, and with an equivalent or safer toxicity profile. Also, there is no risk of addiction. Concern had been raised over a possible cross-sensitisation with neuromuscular blocking agents. While a recent assessment of the available data by the European Medicines Agency (EMA) has confirmed the favourable risk-benefit ratio of pholcodine, further studies are needed to clear this point. Copyright © 2013 Société Française de Pharmacologie et de Thérapeutique. Publié par Elsevier Masson SAS.

  3. [Not Available].

    PubMed

    Bentué-Ferrer, Danièle; Tribut, Olivier; Verdier, Marie-Clemence

    2010-01-01

    Vigabatrin is a second generation anticonvulsant drug available in France since 1995. It is an amino acid analogue of the GABA, marketed under the racemic form [R(-)/S(+)50/50], but only the S(+)-enantiomer is active. Neither the mechanism of action of vigabatrin, an irreversible enzymatic inhibition, nor its pharmacokinetic characteristics (no binding to plasma proteins, low metabolism, no interaction with CYP), are in favour of TDM. There is no validated therapeutic range, but to the recommended dosage of 1 to 3g a day correspond plasma concentrations ranging from 0,8 to 36 mg/L (6 - 279 µmol/L). For this molecule, the level of proof of the interest of the TDM was estimated in: to be useless.

  4. [Not Available].

    PubMed

    Bouquié, Régis; Dailly, Eric; Bentué-Ferrer, Danièle

    2010-01-01

    Oxcarbazepine is an analogue of carbamazepine, used for the treatment of partial seizure with or without secondary generalization. The two forms R and S of the mono-hydroxylated derivatives (MHD) are responsible for most of the anti-convulsant activity and it is the concentrations of MHD that are relevant in therapeutic drug monitoring (TDM). Analysis of currently literature provides no well-established relationship between plasma concentration of MHD and efficiency or toxicity. Although there is not a validated therapeutic range, the residual concentrations of usually observed therapeutic MHD are situated between 12 and 30 mg/L. In certain pathological or physiological circumstances, the pharmacokinetic variability of the oxcarbazepine can be considerable, but this strong unpredictability does not nevertheless justify the TDM of the MHD. Based on the available evidence, TDM of MHD is not routinely warranted but may be possibly useful in specific situations such as pregnancy or renal insufficiency.

  5. [Not Available].

    PubMed

    Jelassi, Mohamed Larbi; Benlmouden, Amine; Lefeuvre, Sandrine; Mainardi, Jean-Luc; Billaud, Eliane M

    2011-01-01

    Level of Evidence for Therapeutic Drug Monitoring of Vancomycin. Vancomycin is an antibiotic for exclusive hospital use administrated in intravenous infusion to treat systemic infections. It is mainly eliminated by kidneys and potentially nephrotoxic. Data available show that Therapeutic Drug Monitoring (TDM) of vancomycin is highly recommended. It aims to ensure efficacy and avoid resistance by maintaining trough plasma concentrations above the MIC. Secondary, vancomycine TDM may be indicated to prevent nephrotoxicity in high risk patients. TDM is often underwent at steady state (48 to 72 h after the treatment initiation) unless in case of renal impairment (24 h). While compared with intermittent administration, continuous infusion did not result in prognosis improvement; however it resulted in lower pharmacokinetic variability and better cost-efficiency. Targeted trough concentrations for intermittent infusion are between 15 and 20 mg/L (up to 25-30 mg/L for GISA). In case of continuous infusion, targets are higher (25 to 40 mg/L).

  6. Fabrication of biomimetic superhydrophobic surfaces inspired by lotus leaf and silver ragwort leaf

    NASA Astrophysics Data System (ADS)

    Lin, Jinyou; Cai, Yu; Wang, Xianfeng; Ding, Bin; Yu, Jianyong; Wang, Moran

    2011-03-01

    Inspired by the self-cleaning lotus leaf and silver ragwort leaf, here we demonstrate the fabrication of biomimetic superhydrophobic fibrous mats via electrospinning polystyrene (PS) solution in the presence of silica nanoparticles. The resultant electrospun fiber surfaces exhibited a fascinating structure with the combination of nano-protrusions and numerous grooves due to the rapid phase separation in electrospinning. The content of silica nanoparticles incorporated into the fibers proved to be the key factor affecting the fiber surface morphology and hydrophobicity. The PS fibrous mats containing 14.3 wt% silica nanoparticles showed a stable superhydrophobicity with a water contact angle as high as 157.2°, exceeding that (147°) of the silver ragwort leaf and approaching that (160°) of the lotus leaf. The superhydrophobicity was explained by the hierarchical surfaces increasing the surface roughness which trapped more air under the water droplets that fell on the fibers.Inspired by the self-cleaning lotus leaf and silver ragwort leaf, here we demonstrate the fabrication of biomimetic superhydrophobic fibrous mats via electrospinning polystyrene (PS) solution in the presence of silica nanoparticles. The resultant electrospun fiber surfaces exhibited a fascinating structure with the combination of nano-protrusions and numerous grooves due to the rapid phase separation in electrospinning. The content of silica nanoparticles incorporated into the fibers proved to be the key factor affecting the fiber surface morphology and hydrophobicity. The PS fibrous mats containing 14.3 wt% silica nanoparticles showed a stable superhydrophobicity with a water contact angle as high as 157.2°, exceeding that (147°) of the silver ragwort leaf and approaching that (160°) of the lotus leaf. The superhydrophobicity was explained by the hierarchical surfaces increasing the surface roughness which trapped more air under the water droplets that fell on the fibers. Electronic

  7. Photosynthetic nutrient-use efficiency in three fast-growing tropical trees with differing leaf longevities.

    PubMed

    Hiremath, A J

    2000-08-01

    Differences in nutrient-use efficiency have been attributed to differences in leaf habit. It has been suggested that evergreens, with their longer-lived leaves, and therefore longer nutrient retention, are more efficient than deciduous species in their use of nutrients. In tropical trees, however, leaf life span is not always a function of whole-tree deciduousness, leading to the proposal that nutrient-use efficiency is better related to leaf life span than to leaf habit. It was predicted that potential photosynthetic nutrient-use efficiency (maximum potential photosynthesis/leaf nutrient content) would decrease with increasing leaf life span, whereas cumulative photosynthetic nutrient-use efficiency (carbon assimilated over a leaf's life span/total nutrients invested in a leaf) would increase with increasing leaf life span. Potential and cumulative photosynthetic nutrient-use efficiencies (with respect to nitrogen and phosphorus) were measured for three fast-growing tropical trees: Cedrela odorata L. (Meliaceae), Cordia alliodora (R. & P.) Cham. (Boraginaceae), and Hyeronima alchorneoides Allemão (Euphorbiaceae). Mean leaf life spans of the three species varied about threefold and ranged from 50 to 176 days. The predictions were partially supported: Cedrela odorata had the shortest-lived leaves and the highest potential nitrogen-use efficiency, whereas Hyeronima alchorneoides had the longest-lived leaves and the highest cumulative nitrogen- and phosphorus-use efficiencies. Potential phosphorus-use efficiency, however, was invariant among species. It is suggested that there are potential tradeoffs between leaf characteristics that lead to high potential and cumulative nutrient-use efficiencies. High potential nutrient-use efficiency may be beneficial in high-nutrient environments, whereas high cumulative nutrient-use efficiency may be of greater benefit to species in low-nutrient environments.

  8. Comparative performance assessment of commercially available automatic external defibrillators: A simulation and real-life measurement study of hands-off time.

    PubMed

    Savastano, Simone; Vanni, Vincenzo; Burkart, Roman; Raimondi, Maurizio; Canevari, Fabrizio; Molinari, Simone; Baldi, Enrico; Danza, Aurora I; Caputo, Maria Luce; Mauri, Romano; Regoli, Francois; Conte, Giulio; Benvenuti, Claudio; Auricchio, Angelo

    2017-01-01

    Early and good quality cardiopulmonary resuscitation (CPR) and the use of automated external defibrillators (AEDs) improve cardiac arrest patients' survival. However, AED peri- and post-shock/analysis pauses may reduce CPR effectiveness. The time performance of 12 different commercially available AEDs was tested in a manikin based scenario; then the AEDs recordings from the same tested models following the clinical use both in Pavia and Ticino were analyzed to evaluate the post-shock and post-analysis time. None of the AEDs was able to complete the analysis and to charge the capacitors in less than 10s and the mean post-shock pause was 6.7±2.4s. For non-shockable rhythms, the mean analysis time was 10.3±2s and the mean post-analysis time was 6.2±2.2s. We analyzed 154 AED records [104 by Emergency Medical Service (EMS) rescuers; 50 by lay rescuers]. EMS rescuers were faster in resuming CPR than lay rescuers [5.3s (95%CI 5-5.7) vs 8.6s (95%CI 7.3-10). AEDs showed different performances that may reduce CPR quality mostly for those rescuers following AED instructions. Both technological improvements and better lay rescuers training might be needed. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  9. [Not Available].

    PubMed

    Dufour, Sarah; Lavergne, Chantal; Ramos, Yuddy

    2016-03-14

    The objectives of this study were to 1) map the geographic distribution of rates of children reported to Montreal child protective services by ethnocultural group (Black, other visible minorities, not from visible minorities) and 2) estimate the relative contribution of different territorial characteristics to the rates for those groups. The study covered the 505 Montreal-area census tracts for which complete data were available. The reporting rates by group (dependent variables) and various territorial characteristics such as poverty (independent variables) were mapped and subjected to multiple linear regression and geographically weighted regression. The results of the geographically weighted regression were then mapped. The geographic distribution and reporting rates varied greatly by group, with the Black children having the highest rates. Although territorial characteristics explained 51% of variance for the children who were not members of visible minorities, they were clearly less effective in predicting rates in the case of Black children (18%) and other minorities (18%). Already well-known territorial risk factors are at work in Montreal, but their influence is not equally strong in all census tracts nor, especially, in all ethnocultural groups. Therefore, when only the distribution and prediction of reports for all children as a whole are examined, important differences are underestimated. Access to and appropriateness of services offered to vulnerable families, including those of visible minorities, could, however, be improved with a better understanding of local dynamics.

  10. [Not Available].

    PubMed

    Calbiac, Pascale De; Lamoureux, Fabien; Pourrat, Xavier; Bretault, Lydia; Marchand, Sophie; Grassin, Jacqueline; Antier, Daniel

    2006-01-01

    Treatment of Bronchial Superinfections: Data Related to Stability of Antibiotics in Portable Pumps. Given many data about the stability of antibiotics in portable pump (elastomer) are lacking, this study was designed to make a point about available data and to evaluate the stability of antibiotics when exposed to temperature within 35°C (average temperature measured in real conditions of use). First, to collect information about the stability of antibiotics in portable pump and to confront them with the local antibiotics protocols dedicated to the treatment of bronchial superinfection in patients with cystic fibrosis; second, to evaluate the stability of piperacillin associated with tazobactam at 35°C. While measured concentrations in tazobactam did not show significant variation during the study, piperacillin measurements showed a major reduction of concentration (up to 33%), both time and concentration related to. Such information must be pointed out to prescribers and patients to ensure a cold accumulator is placed in the pump can'ying-bag and to limit the duration of infusion to 24h with a single pump. This experimental program will keep on going with the stability study of both ticarcillin and cefsulodin in portable pump. Copyright © 2006 Société Française de Pharmacologie et de Thérapeutique. Publié par Elsevier Masson SAS.

  11. [Not Available].

    PubMed

    Demaeyer, Ph

    2016-01-01

    Medicine owes many to Hippocrate, but pneumology traces its origin back to antiquity, from Mesopotamia to ancient Rome. Regarding prehistory: if viscera of this period have not been kept, some bones were. Since Neanderthals, it is then possible to study osteoarticular pathologies (often chronic arthrosis). But no evidence of tuberculosis was found (all thoracic kyphosis are not tuberculosis). Tuberculosis probably appears during the Neolithic age, because of high concentration of population. In ancient times, pneumology was of course not a real medical specialty. However, respiratory illness already constituted a big part of antique medical practice. The purpose of the physician in antiquity was to establish a diagnosis, a prognostic and to propose a treatment. Prognostic revealed to be of great importance in ancient times, since therapeutic efficacy was limited. Contemporary physicians often neglect this part of their practice. In ancient times, physicians also tried to gradually eliminate magic-religious aspects in taking care of the patients. This review will propose a journey from Mesopotamia to ancient Egypt (and its medical papyrus). Very few sources are available concerning medicine in pre-Columbian cultures. However, it is well known that shamans had, besides their religious competences, a great pharmacopoeia. Because of these very few sources, this topic will not be added to this article. Little is known in Europa about chinese medicine before the Jesuit mission in China during the 17th and 18th centuries. Yet, chinese medicine grew in parallel with European's one. Some relevant elements of this medicine will hereafter be shown.

  12. Influence of Vegetation Structure on Lidar-derived Canopy Height and Fractional Cover in Forested Riparian Buffers During Leaf-Off and Leaf-On Conditions

    PubMed Central

    Wasser, Leah; Day, Rick; Chasmer, Laura; Taylor, Alan

    2013-01-01

    Estimates of canopy height (H) and fractional canopy cover (FC) derived from lidar data collected during leaf-on and leaf-off conditions are compared with field measurements from 80 forested riparian buffer plots. The purpose is to determine if existing lidar data flown in leaf-off conditions for applications such as terrain mapping can effectively estimate forested riparian buffer H and FC within a range of riparian vegetation types. Results illustrate that: 1) leaf-off and leaf-on lidar percentile estimates are similar to measured heights in all plots except those dominated by deciduous compound-leaved trees where lidar underestimates H during leaf off periods; 2) canopy height models (CHMs) underestimate H by a larger margin compared to percentile methods and are influenced by vegetation type (conifer needle, deciduous simple leaf or deciduous compound leaf) and canopy height variability, 3) lidar estimates of FC are within 10% of plot measurements during leaf-on periods, but are underestimated during leaf-off periods except in mixed and conifer plots; and 4) depth of laser pulse penetration lower in the canopy is more variable compared to top of the canopy penetration which may influence within canopy vegetation structure estimates. This study demonstrates that leaf-off lidar data can be used to estimate forested riparian buffer canopy height within diverse vegetation conditions and fractional canopy cover within mixed and conifer forests when leaf-on lidar data are not available. PMID:23382966

  13. Influence of vegetation structure on lidar-derived canopy height and fractional cover in forested riparian buffers during leaf-off and leaf-on conditions.

    PubMed

    Wasser, Leah; Day, Rick; Chasmer, Laura; Taylor, Alan

    2013-01-01

    Estimates of canopy height (H) and fractional canopy cover (FC) derived from lidar data collected during leaf-on and leaf-off conditions are compared with field measurements from 80 forested riparian buffer plots. The purpose is to determine if existing lidar data flown in leaf-off conditions for applications such as terrain mapping can effectively estimate forested riparian buffer H and FC within a range of riparian vegetation types. Results illustrate that: 1) leaf-off and leaf-on lidar percentile estimates are similar to measured heights in all plots except those dominated by deciduous compound-leaved trees where lidar underestimates H during leaf off periods; 2) canopy height models (CHMs) underestimate H by a larger margin compared to percentile methods and are influenced by vegetation type (conifer needle, deciduous simple leaf or deciduous compound leaf) and canopy height variability, 3) lidar estimates of FC are within 10% of plot measurements during leaf-on periods, but are underestimated during leaf-off periods except in mixed and conifer plots; and 4) depth of laser pulse penetration lower in the canopy is more variable compared to top of the canopy penetration which may influence within canopy vegetation structure estimates. This study demonstrates that leaf-off lidar data can be used to estimate forested riparian buffer canopy height within diverse vegetation conditions and fractional canopy cover within mixed and conifer forests when leaf-on lidar data are not available.

  14. [The influence of human milk and various artificial formulae commercially available in Spain on the fatty acid status of infants in the first two months of life].

    PubMed

    Benito Fernández, J; Ruiz Sanz, J I; Aquino Fariña, L; Pijoán Zubizarreta, J I; Sasieta Altuna, M; Sanjurjo Crespo, P

    2002-08-01

    To evaluate changes in the fatty acid composition of red blood cell phospholipids in breast-fed infants compared with those in infants fed with different formulas (conventional, omega -6-enriched formula, omega -6- and omega -3-enriched formula and nucleotide-enriched formula). Thirty-seven healthy term infants were randomly assigned to one of five different feeding groups. Weight, length, head circumference, and arm circumference were assessed at 7 and 60 days of age. The fatty acid composition of the infants' red blood cell phosphatidylcholine (PC) and phosphatidylethanolamine (PE) were analyzed at these ages. The anthropometric variables studied showed no changes among the different groups. At 60 days old, arachidonic acid concentration (20:4 omega -6) was lower in non-omega -6 enriched formula-fed groups compared with that in the breast-milk fed group (4.03, 3.68 and 5.15 vs 7.20 g/100 g of fatty acids). Docosahexaenoic acid concentration (22:6omega -3) in both PC and PE clearly decreased in the non-omega -3 formula-fed groups compared with that in the breast-milk fed group (PC: 0.72 vs 2.82 g/100 g of fatty acids and PE: 5.15 vs 7.73 g/100 g of fatty acids). This study demonstrates differences in the fatty acid composition of red blood cell phospholipids between breast-milk fed infants and those fed with any of the artificial formulas available on the Spanish market. These data provide evidence of the influence of diet on certain essential fatty acids in the body.

  15. Trade-offs between leaf hydraulic capacity and drought vulnerability: morpho-anatomical bases, carbon costs and ecological consequences.

    PubMed

    Nardini, Andrea; Pedà, Giulia; La Rocca, Nicoletta

    2012-11-01

    Leaf hydraulic conductance (K(leaf) ) and vulnerability constrain plant productivity, but no clear trade-off between these fundamental functional traits has emerged in previous studies. We measured K(leaf) on a leaf area (K(leaf_area)) and mass basis (K(leaf_mass)) in six woody angiosperms, and compared these values with species' distribution and leaf tolerance to dehydration in terms of P(50), that is, the leaf water potential inducing 50% loss of K(leaf) . We also measured several morphological and anatomical traits associated with carbon investment in leaf construction and water transport efficiency. Clear relationships emerged between K(leaf_mass), P(50), and leaf mass per unit area (LMA), suggesting that increased tolerance to hydraulic dysfunction implies increased carbon costs for leaf construction and water use. Low P(50) values were associated with narrower and denser vein conduits, increased thickness of conduit walls, and increased vein density. This, in turn, was associated with reduced leaf surface area. Leaf P(50) was closely associated with plants' distribution over a narrow geographical range, suggesting that this parameter contributes to shaping vegetation features. Our data also highlight the carbon costs likely to be associated with increased leaf tolerance to hydraulic dysfunction, which confers on some species the ability to thrive under reduced water availability but decreases their competitiveness in high-resource habitats. © 2012 The Authors. New Phytologist © 2012 New Phytologist Trust.

  16. Intraspecific growth and functional leaf trait responses to natural soil resource gradients for conifer species with contrasting leaf habit.

    PubMed

    Walters, Michael B; Gerlach, John P

    2013-03-01

    Interspecific relationships among species mean leaf traits, performance and species resource/climate distributions help provide the foundation for a predictive, functionally based plant ecology. Intraspecific responses of leaf traits and performance to resource gradients and how these vary among species may be equally important but have received less attention. Here, we examine relationships between proxies of soil resource availability, leaf traits and growth (height at 25 years, SI25) for winter deciduous Larix decidua Mill. and evergreen Pinus resinosa Ait. trees distributed over soil resource gradients in the Great Lakes region of North America. We predicted that (i) leaf trait responses to soil resources within species will be similar to reported distributions of mean leaf traits over soil resource gradients among species; (ii) soil resource-related variation in leaf traits can help explain SI25; and (iii) SI25 will be greater for Larix than Pinus at higher soil resources and greater for Pinus than Larix at lower soil resources and this pattern will be associated with species differences in leaf trait responses to soil resources. Among the measured leaf traits (live N, Mg, Ca, K, P, and Mn, litter N, N resorption, carbon isotope discrimination, specific leaf area, lifespan), soil resources only impacted live and litter N for both species and K for Pinus. In turn, only the leaf traits responsive to soil resources affected SI25 in the expected manner. Larix had greater SI25 than Pinus across soil resource gradients and both species had similar growth and leaf trait sensitivities to resources. In summary: (i) several leaf traits reported to be associated with performance and edaphic distributions across species were, within species, unresponsive to nitrogen and water availability and unrelated to growth; (ii) leaf N showed high plasticity to soil resources and this plasticity was functionally relevant to growth over its entire range of response; (iii) large

  17. Leaf absorbance and photosynthesis

    NASA Technical Reports Server (NTRS)

    Schurer, Kees

    1994-01-01

    The absorption spectrum of a leaf is often thought to contain some clues to the photosynthetic action spectrum of chlorophyll. Of course, absorption of photons is needed for photosynthesis, but the reverse, photosynthesis when there is absorption, is not necessarily true. As a check on the existence of absorption limits we measured spectra for a few different leaves. Two techniques for measuring absorption have been used, viz. the separate determination of the diffuse reflectance and the diffuse transmittance with the leaf at a port of an integrating sphere and the direct determination of the non-absorbed fraction with the leaf in the sphere. In a cross-check both methods yielded the same results for the absorption spectrum. The spectrum of a Fuchsia leaf, covering the short-wave region from 350 to 2500 nm, shows a high absorption in UV, blue and red, the well known dip in the green and a steep fall-off at 700 nm. Absorption drops to virtually zero in the near infrared, with subsequent absorptions, corresponding to the water absorption bands. In more detailed spectra, taken at 5 nm intervals with a 5 nm bandwidth, differences in chlorophyll content show in the different depths of the dip around 550 nm and in a small shift of the absorption edge at 700 nm. Spectra for Geranium (Pelargonium zonale) and Hibiscus (with a higher chlorophyll content) show that the upper limit for photosynthesis can not be much above 700 nm. No evidence, however, is to be seen of a lower limit for photosynthesis and, in fact, some experiments down to 300 nm still did not show a decrease of the absorption although it is well recognized that no photosynthesis results with 300 nm wavelengths.

  18. Co-occurrence of trees with different leaf habit: A functional approach on Mediterranean oaks

    NASA Astrophysics Data System (ADS)

    Damesin, Claire; Rambal, Serge; Joffre, Richard

    1998-06-01

    Tree species can be split into two groups in terms of their leaf life-spans: evergreens and deciduous. Their distinct geographical distribution suggests that these two groups have functional characteristics adapted to specific environments. However, deciduous and evergreen trees co-exist in some regions, such as those with a Mediterranean climate. They provide good models for comparing the properties of both trees and obtaining an understanding of how diversity is maintained. This is the case in southern France, where the evergreen holm oak ( Quercus ilex) and the deciduous downy oak ( Quercus pubescens) co-exist. A research programme has been conducted which compares the functioning of these two species at various scales, with the aim of anticipating their distribution in the event of climatic change. The 'cost-benefit' model of Mooney and Dunn has been tested at leaf scale. Q. pubescens has a lower area-based construction cost than Q. ilex, but does not have a higher photosynthetic capacity. Despite differences in biochemical composition, size and mass per unit area, the leaves of the two species respond similarly to limited water conditions. Furthermore, the carbon isotope composition suggests that they have similar intrinsic water-use efficiencies. At the ecosystem scale, preliminary data are available on water, carbon and nitrogen use: i) measurements of leaf water potentials show that drought constraint starts at the same time and with the same rate and intensity in both species; ii) leaf area index was higher in Q. ilex woodlands; and iii) the release rate of nitrogen from the litter was faster in Q. ilex ecosystems. Together, these results indicate that the key factors distinguishing functions of deciduous and evergreen Quercus are more apparent at the ecosystem level than at the leaf level.

  19. Allometric method to estimate leaf area index for row crops

    USDA-ARS?s Scientific Manuscript database

    Leaf area index (LAI) is critical for predicting plant metabolism, biomass production, evapotranspiration, and greenhouse gas sequestration, but direct LAI measurements are difficult and labor intensive. Several methods are available to measure LAI indirectly or calculate LAI using allometric method...

  20. The oxygen isotope enrichment of leaf-exported assimilates--does it always reflect lamina leaf water enrichment?

    PubMed

    Gessler, Arthur; Brandes, Elke; Keitel, Claudia; Boda, Sonja; Kayler, Zachary E; Granier, André; Barbour, Margaret; Farquhar, Graham D; Treydte, Kerstin

    2013-10-01

    The oxygen stable isotope composition of plant organic matter (OM) (particularly of wood and cellulose in the tree ring archive) is valuable in studies of plant-climate interaction, but there is a lack of information on the transfer of the isotope signal from the leaf to heterotrophic tissues. We studied the oxygen isotopic composition and its enrichment above source water of leaf water over diel courses in five tree species covering a broad range of life forms. We tracked the transfer of the isotopic signal to leaf water-soluble OM and further to phloem-transported OM. Observed leaf water evaporative enrichment was consistent with values predicted from mechanistic models taking into account nonsteady-state conditions. While leaf water-soluble OM showed the expected (18)O enrichment in all species, phloem sugars were less enriched than expected from leaf water enrichment in Scots pine (Pinus sylvestris), European larch (Larix decidua) and Alpine ash (Eucalyptus delegatensis). Oxygen atom exchange with nonenriched water during phloem loading and transport, as well as a significant contribution of assimilates from bark photosynthesis, can explain these phloem (18)O enrichment patterns. Our results indicate species-specific uncoupling between the leaf water and the OM oxygen isotope signal, which is important for the interpretation of tree ring data. © 2013 The Authors. New Phytologist © 2013 New Phytologist Trust.

  1. The oxygen isotope enrichment of leaf-exported assimilates – does it always reflect lamina leaf water enrichment?

    PubMed Central

    Gessler, Arthur; Brandes, Elke; Keitel, Claudia; Boda, Sonja; Kayler, Zachary E; Granier, André; Barbour, Margaret; Farquhar, Graham D; Treydte, Kerstin

    2013-01-01

    The oxygen stable isotope composition of plant organic matter (OM) (particularly of wood and cellulose in the tree ring archive) is valuable in studies of plant–climate interaction, but there is a lack of information on the transfer of the isotope signal from the leaf to heterotrophic tissues. We studied the oxygen isotopic composition and its enrichment above source water of leaf water over diel courses in five tree species covering a broad range of life forms. We tracked the transfer of the isotopic signal to leaf water-soluble OM and further to phloem-transported OM. Observed leaf water evaporative enrichment was consistent with values predicted from mechanistic models taking into account nonsteady-state conditions. While leaf water-soluble OM showed the expected 18O enrichment in all species, phloem sugars were less enriched than expected from leaf water enrichment in Scots pine (Pinus sylvestris), European larch (Larix decidua) and Alpine ash (Eucalyptus delegatensis). Oxygen atom exchange with nonenriched water during phloem loading and transport, as well as a significant contribution of assimilates from bark photosynthesis, can explain these phloem 18O enrichment patterns. Our results indicate species-specific uncoupling between the leaf water and the OM oxygen isotope signal, which is important for the interpretation of tree ring data. PMID:23763637

  2. The plant leaf movement analyzer (PALMA): a simple tool for the analysis of periodic cotyledon and leaf movement in Arabidopsis thaliana.

    PubMed

    Wagner, Lucas; Schmal, Christoph; Staiger, Dorothee; Danisman, Selahattin

    2017-01-01

    The analysis of circadian leaf movement rhythms is a simple yet effective method to study effects of treatments or gene mutations on the circadian clock of plants. Currently, leaf movements are analysed using time lapse photography and subsequent bioinformatics analyses of leaf movements. Programs that are used for this purpose either are able to perform one function (i.e. leaf tip detection or rhythm analysis) or their function is limited to specific computational environments. We developed a leaf movement analysis tool-PALMA-that works in command line and combines image extraction with rhythm analysis using Fast Fourier transformation and non-linear least squares fitting. We validated PALMA in both simulated time series and in experiments using the known short period mutant sensitivity to red light reduced 1 (srr1-1). We compared PALMA with two established leaf movement analysis tools and found it to perform equally well. Finally, we tested the effect of reduced iron conditions on the leaf movement rhythms of wild type plants. Here, we found that PALMA successfully detected period lengthening under reduced iron conditions. PALMA correctly estimated the period of both simulated and real-life leaf movement experiments. As a platform-independent console-program that unites both functions needed for the analysis of circadian leaf movements it is a valid alternative to existing leaf movement analysis tools.

  3. Patterns in leaf morphological traits of Chinese woody plants and the application for paleoclimate reconstruction

    NASA Astrophysics Data System (ADS)

    Li, Yaoqi; Wang, Zhiheng

    2017-04-01

    Leaf morphological traits (LMTs) directly influence carbon-uptake and water-loss of plants in different habitats, and hence can be sensitive indicators of plant interaction with climate. The relationships between community-aggregated LMTs and their surrounding climate have been used to reconstruct paleoclimate. However, the uncertainties in its application remain poorly explored. Using distribution maps and LMTs data (leaf margin states, leaf length, leaf width, and length-width product/ratio) of 10480 Chinese woody dicots and dated family-level phylogenies, we demonstrated the variations of LMTs in geographical patterns, and analyzed their relationships with climate across different life-forms (evergreen and deciduous; trees, shrubs and lianas) and species quartiles with different family-ages. Results showed that from southern to northern China, leaves became shorter and narrower, while leaf length-width ratio increased and toothed-margin percentage decreased. Our results revealed great uncertainties in leaf margin-temperature relationships induced by life-form, precipitation and evolutionary history, and suggested that the widely-used method, leaf margin analysis, should be applied cautiously on paleotemperature reconstruction. Differently, mean leaf size responded tightly to spatial variations in annual evapotranspiration (AET) and primary productivity (GPP and NPP), and these relationships remained constant across different life-forms and evolutionary history, suggesting that leaf size could be a useful surrogate for paleo primary productivity.

  4. Phenotypic selection on leaf ecophysiological traits in Helianthus.

    PubMed

    Donovan, L A; Ludwig, F; Rosenthal, D M; Rieseberg, L H; Dudley, S A

    2009-08-01

    Habitats that differ in soil resource availability are expected to differ for selection on resource-related plant traits. Here, we examined spatial and temporal variation in phenotypic selection on leaf ecophysiological traits for 10 Helianthus populations, including two species of hybrid origin, Helianthus anomalus and Helianthus deserticola, and artificial hybrids of their ancestral parents. Leaf traits assessed were leaf size, succulence, nitrogen (N) concentration and water-use efficiency (WUE). Biomass and leaf traits of artificial hybrids indicate that the actively moving dune habitat of H. anomalus was more growth limiting, with lower N availability but higher relative water availability than the stabilized dune habitat of H. deserticola. Habitats differed for direct selection on leaf N and WUE, but not size or succulence, for the artificial hybrids. However, within the H. anomalus habitat, direct selection on WUE also differed among populations. Across years, direct selection on leaf traits did not differ. Leaf N was the only trait for which direct selection differed between habitats but not within the H. anomalus habitat, suggesting that nutrient limitation is an important selective force driving adaptation of H. anomalus to the active dune habitat.

  5. Changes in clonal poplar leaf chemistry caused by stem galls alter herbivory and leaf litter decomposition.

    PubMed

    Künkler, Nora; Brandl, Roland; Brändle, Martin

    2013-01-01

    Gall-inducing insects are highly specialized herbivores that modify the phenotype of their host plants. Beyond the direct manipulation of plant morphology and physiology in the immediate environment of the gall, there is also evidence of plant-mediated effects of gall-inducing insects on other species of the assemblages and ecosystem processes associated with the host plant. We analysed the impact of gall infestation by the aphid Pemphigus spirothecae on chemical leaf traits of clonal Lombardy poplars (Populus nigra var. italica) and the subsequent effects on intensity of herbivory and decomposition of leaves across five sites. We measured the herbivory of two feeding guilds: leaf-chewing insects that feed on the blade (e.g. caterpillars and sawfly larvae) and skeletonising insects that feed on the mesophyll of the leaves (e.g. larvae of beetles). Galled leaves had higher phenol (35%) and lower nitrogen and cholorophyll contents (35% respectively 37%) than non-galled leaves, and these differences were stronger in August than in June. Total herbivory intensity was 27% higher on galled than on non-galled leaves; damage by leaf chewers was on average 61% higher on gall infested leaves, whereas damage by skeletonising insects was on average 39% higher on non-galled leaves. After nine months the decomposition rate of galled leaf litter was 15% lower than that of non-galled leaf litter presumably because of the lower nitrogen content of the galled leaf litter. This indicated after-life effects of gall infestation on the decomposers. We found no evidence for galling x environment interactions.

  6. Plant traits and environment: floating leaf blade production and turnover of waterlilies.

    PubMed

    Klok, Peter F; van der Velde, Gerard

    2017-01-01

    Floating leaf blades of waterlilies fulfill several functions in wetland ecosystems by production, decomposition and turnover as well as exchange processes. Production and turnover rates of floating leaf blades of three waterlily species, Nuphar lutea (L.) Sm., Nymphaea alba L. and Nymphaea candida Presl, were studied in three freshwater bodies, differing in trophic status, pH and alkalinity. Length and percentages of leaf loss of marked leaf blades were measured weekly during the growing season. Area and biomass were calculated based on leaf length and were used to calculate the turnover rate of floating leaf blades. Seasonal changes in floating leaf production showed that values decreased in the order: Nymphaea alba, Nuphar lutea, Nymphaea candida. The highest production was reached for Nuphar lutea and Nymphaea alba in alkaline, eutrophic water bodies. The production per leaf was relatively high for both species in the acid water body. Nymphaea candida showed a very short vegetation period and low turnover rates. The ratio Total potential leaf biomass/Maximum potential leaf biomass (P/Bmax) of the three species ranged from 1.35-2.25. The ratio Vegetation period (Period with floating leaves)/Mean leaf life span ranged from 2.94-4.63, the ratio Growth period (Period with appearance of new floating leaves)/Vegetation period from 0.53-0.73. The clear differences between Nymphaea candida versus Nuphar lutea and Nymphaea alba, may be due to adaptations of Nymphaea candida to an Euro-Siberic climate with short-lasting summer conditions.

  7. The worldwide leaf economics spectrum.

    PubMed

    Wright, Ian J; Reich, Peter B; Westoby, Mark; Ackerly, David D; Baruch, Zdravko; Bongers, Frans; Cavender-Bares, Jeannine; Chapin, Terry; Cornelissen, Johannes H C; Diemer, Matthias; Flexas, Jaume; Garnier, Eric; Groom, Philip K; Gulias, Javier; Hikosaka, Kouki; Lamont, Byron B; Lee, Tali; Lee, William; Lusk, Christopher; Midgley, Jeremy J; Navas, Marie-Laure; Niinemets, Ulo; Oleksyn, Jacek; Osada, Noriyuki; Poorter, Hendrik; Poot, Pieter; Prior, Lynda; Pyankov, Vladimir I; Roumet, Catherine; Thomas, Sean C; Tjoelker, Mark G; Veneklaas, Erik J; Villar, Rafael

    2004-04-22

    Bringing together leaf trait data spanning 2,548 species and 175 sites we describe, for the first time at global scale, a universal spectrum of leaf economics consisting of key chemical, structural and physiological properties. The spectrum runs from quick to slow return on investments of nutrients and dry mass in leaves, and operates largely independently of growth form, plant functional type or biome. Categories along the spectrum would, in general, describe leaf economic variation at the global scale better than plant functional types, because functional types overlap substantially in their leaf traits. Overall, modulation of leaf traits and trait relationships by climate is surprisingly modest, although some striking and significant patterns can be seen. Reliable quantification of the leaf economics spectrum and its interaction with climate will prove valuable for modelling nutrient fluxes and vegetation boundaries under changing land-use and climate.

  8. Antimicrobial Compounds from Leaf Extracts of Jatropha curcas, Psidium guajava, and Andrographis paniculata

    PubMed Central

    Rahman, M. M.; Ahmad, S. H.; Mohamed, M. T. M.; Ab Rahman, M. Z.

    2014-01-01

    The present research was conducted to discover antimicrobial compounds in methanolic leaf extracts of Jatropha curcas and Andrographis paniculata and ethanolic leaf extract of Psidium guajava and the effectiveness against microbes on flower preservative solution of cut Mokara Red orchid flowers was evaluated. The leaves were analyzed using gas chromatography-mass spectrometry. A total of nine, 66, and 29 compounds were identified in J. curcas, P. guajava, and A. paniculata leaf extracts, with five (88.18%), four (34.66%), and three (50.47%) having unique antimicrobial compounds, respectively. The experimental design on vase life was conducted using a completely randomized design with 10 replications. The flower vase life was about 6 days in the solution containing the P. guajava and A. paniculata leaf extracts at 15mg/L. Moreover, solution with leaf extracts of A. paniculata had the lowest bacterial count compared to P. guajava and J. curcas. Thus, these leaf extracts revealed the presence of relevant antimicrobial compounds. The leaf extracts have the potential as a cut flower solution to minimize microbial populations and extend flower vase life. However, the activities of specific antimicrobial compounds and double or triple combination leaf extracts to enhance the effectiveness to extend the vase life need to be tested. PMID:25250382

  9. Antimicrobial compounds from leaf extracts of Jatropha curcas, Psidium guajava, and Andrographis paniculata.

    PubMed

    Rahman, M M; Ahmad, S H; Mohamed, M T M; Ab Rahman, M Z

    2014-01-01

    The present research was conducted to discover antimicrobial compounds in methanolic leaf extracts of Jatropha curcas and Andrographis paniculata and ethanolic leaf extract of Psidium guajava and the effectiveness against microbes on flower preservative solution of cut Mokara Red orchid flowers was evaluated. The leaves were analyzed using gas chromatography-mass spectrometry. A total of nine, 66, and 29 compounds were identified in J. curcas, P. guajava, and A. paniculata leaf extracts, with five (88.18%), four (34.66%), and three (50.47%) having unique antimicrobial compounds, respectively. The experimental design on vase life was conducted using a completely randomized design with 10 replications. The flower vase life was about 6 days in the solution containing the P. guajava and A. paniculata leaf extracts at 15 mg/L. Moreover, solution with leaf extracts of A. paniculata had the lowest bacterial count compared to P. guajava and J. curcas. Thus, these leaf extracts revealed the presence of relevant antimicrobial compounds. The leaf extracts have the potential as a cut flower solution to minimize microbial populations and extend flower vase life. However, the activities of specific antimicrobial compounds and double or triple combination leaf extracts to enhance the effectiveness to extend the vase life need to be tested.

  10. 7 CFR 29.3033 - Leaf.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Leaf. 29.3033 Section 29.3033 Agriculture Regulations... Leaf. Whole, unstemmed leaf. Leaf, when applied to tobacco in strip form, shall describe the divided unit of a whole leaf. [49 FR 16758, Apr. 20, 1984] ...

  11. 7 CFR 29.3525 - Leaf.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 7 Agriculture 2 2011-01-01 2011-01-01 false Leaf. 29.3525 Section 29.3525 Agriculture Regulations... Type 95) § 29.3525 Leaf. Whole, unstemmed leaf. Leaf, when applied to tobacco in strip form, shall describe the divided unit of a whole leaf. [49 FR 16759, Apr. 20, 1984] ...

  12. 7 CFR 29.3033 - Leaf.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 7 Agriculture 2 2014-01-01 2014-01-01 false Leaf. 29.3033 Section 29.3033 Agriculture Regulations... Leaf. Whole, unstemmed leaf. Leaf, when applied to tobacco in strip form, shall describe the divided unit of a whole leaf. ...

  13. 7 CFR 29.3525 - Leaf.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 7 Agriculture 2 2014-01-01 2014-01-01 false Leaf. 29.3525 Section 29.3525 Agriculture Regulations... Type 95) § 29.3525 Leaf. Whole, unstemmed leaf. Leaf, when applied to tobacco in strip form, shall describe the divided unit of a whole leaf. ...

  14. 7 CFR 29.3525 - Leaf.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 7 Agriculture 2 2012-01-01 2012-01-01 false Leaf. 29.3525 Section 29.3525 Agriculture Regulations... Type 95) § 29.3525 Leaf. Whole, unstemmed leaf. Leaf, when applied to tobacco in strip form, shall describe the divided unit of a whole leaf. [49 FR 16759, Apr. 20, 1984] ...

  15. 7 CFR 29.1028 - Leaf.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 7 Agriculture 2 2014-01-01 2014-01-01 false Leaf. 29.1028 Section 29.1028 Agriculture Regulations... Type 92) § 29.1028 Leaf. Whole, unstemmed leaf. Leaf, when applied to tobacco in strip form, shall describe the divided unit of a whole leaf. ...

  16. 7 CFR 29.3033 - Leaf.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 7 Agriculture 2 2012-01-01 2012-01-01 false Leaf. 29.3033 Section 29.3033 Agriculture Regulations... Leaf. Whole, unstemmed leaf. Leaf, when applied to tobacco in strip form, shall describe the divided unit of a whole leaf. [49 FR 16758, Apr. 20, 1984] ...

  17. 7 CFR 29.3033 - Leaf.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 7 Agriculture 2 2013-01-01 2013-01-01 false Leaf. 29.3033 Section 29.3033 Agriculture Regulations... Leaf. Whole, unstemmed leaf. Leaf, when applied to tobacco in strip form, shall describe the divided unit of a whole leaf. ...

  18. 7 CFR 29.3033 - Leaf.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 7 Agriculture 2 2011-01-01 2011-01-01 false Leaf. 29.3033 Section 29.3033 Agriculture Regulations... Leaf. Whole, unstemmed leaf. Leaf, when applied to tobacco in strip form, shall describe the divided unit of a whole leaf. [49 FR 16758, Apr. 20, 1984] ...

  19. 7 CFR 29.2528 - Leaf.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 7 Agriculture 2 2013-01-01 2013-01-01 false Leaf. 29.2528 Section 29.2528 Agriculture Regulations...-Cured Tobacco (u.s. Types 22, 23, and Foreign Type 96) § 29.2528 Leaf. Whole, unstemmed leaf. Leaf, when applied to tobacco in strip form, shall describe the divided unit of a whole leaf. ...

  20. 7 CFR 29.1028 - Leaf.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Leaf. 29.1028 Section 29.1028 Agriculture Regulations... Type 92) § 29.1028 Leaf. Whole, unstemmed leaf. Leaf, when applied to tobacco in strip form, shall describe the divided unit of a whole leaf. [49 FR 16755, Apr. 20, 1984. Redesignated at 51 FR 25027, July...

  1. 7 CFR 29.1028 - Leaf.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 7 Agriculture 2 2011-01-01 2011-01-01 false Leaf. 29.1028 Section 29.1028 Agriculture Regulations... Type 92) § 29.1028 Leaf. Whole, unstemmed leaf. Leaf, when applied to tobacco in strip form, shall describe the divided unit of a whole leaf. [49 FR 16755, Apr. 20, 1984. Redesignated at 51 FR 25027, July...

  2. 7 CFR 29.3525 - Leaf.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 7 Agriculture 2 2013-01-01 2013-01-01 false Leaf. 29.3525 Section 29.3525 Agriculture Regulations... Type 95) § 29.3525 Leaf. Whole, unstemmed leaf. Leaf, when applied to tobacco in strip form, shall describe the divided unit of a whole leaf. ...

  3. 7 CFR 29.1028 - Leaf.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 7 Agriculture 2 2013-01-01 2013-01-01 false Leaf. 29.1028 Section 29.1028 Agriculture Regulations... Type 92) § 29.1028 Leaf. Whole, unstemmed leaf. Leaf, when applied to tobacco in strip form, shall describe the divided unit of a whole leaf. ...

  4. 7 CFR 29.3525 - Leaf.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Leaf. 29.3525 Section 29.3525 Agriculture Regulations... Type 95) § 29.3525 Leaf. Whole, unstemmed leaf. Leaf, when applied to tobacco in strip form, shall describe the divided unit of a whole leaf. [49 FR 16759, Apr. 20, 1984] ...

  5. 7 CFR 29.1028 - Leaf.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 7 Agriculture 2 2012-01-01 2012-01-01 false Leaf. 29.1028 Section 29.1028 Agriculture Regulations... Type 92) § 29.1028 Leaf. Whole, unstemmed leaf. Leaf, when applied to tobacco in strip form, shall describe the divided unit of a whole leaf. [49 FR 16755, Apr. 20, 1984. Redesignated at 51 FR 25027, July...

  6. 7 CFR 29.2528 - Leaf.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 7 Agriculture 2 2014-01-01 2014-01-01 false Leaf. 29.2528 Section 29.2528 Agriculture Regulations...-Cured Tobacco (u.s. Types 22, 23, and Foreign Type 96) § 29.2528 Leaf. Whole, unstemmed leaf. Leaf, when applied to tobacco in strip form, shall describe the divided unit of a whole leaf. ...

  7. Autumn leaf subsidies influence spring dynamics of freshwater plankton communities.

    PubMed

    Fey, Samuel B; Mertens, Andrew N; Cottingham, Kathryn L

    2015-07-01

    While ecologists primarily focus on the immediate impact of ecological subsidies, understanding the importance of ecological subsidies requires quantifying the long-term temporal dynamics of subsidies on recipient ecosystems. Deciduous leaf litter transferred from terrestrial to aquatic ecosystems exerts both immediate and lasting effects on stream food webs. Recently, deciduous leaf additions have also been shown to be important subsidies for planktonic food webs in ponds during autumn; however, the inter-seasonal effects of autumn leaf subsidies on planktonic food webs have not been studied. We hypothesized that autumn leaf drop will affect the spring dynamics of freshwater pond food webs by altering the availability of resources, water transparency, and the metabolic state of ponds. We created leaf-added and no-leaf-added field mesocosms in autumn 2012, allowed mesocosms to ice-over for the winter, and began sampling the physical, chemical, and biological properties of mesocosms immediately following ice-off in spring 2013. At ice-off, leaf additions reduced dissolved oxygen, elevated total phosphorus concentrations and dissolved materials, and did not alter temperature or total nitrogen. These initial abiotic effects contributed to higher bacterial densities and lower chlorophyll concentrations, but by the end of spring, the abiotic environment, chlorophyll and bacterial densities converged. By contrast, zooplankton densities diverged between treatments during the spring, with leaf additions stimulating copepods but inhibiting cladocerans. We hypothesized that these differences between zooplankton orders resulted from resource shifts following leaf additions. These results suggest that leaf subsidies can alter both the short- and long-term dynamics of planktonic food webs, and highlight the importance of fully understanding how ecological subsidies are integrated into recipient food webs.

  8. Do we Underestimate the Importance of Leaf Size in Plant Economics? Disproportional Scaling of Support Costs Within the Spectrum of Leaf Physiognomy

    PubMed Central

    Niinemets, Ülo; Portsmuth, Angelika; Tena, David; Tobias, Mari; Matesanz, Silvia; Valladares, Fernando

    2007-01-01

    Background Broad scaling relationships between leaf size and function do not take into account that leaves of different size may contain different fractions of support in petiole and mid-rib. Methods The fractions of leaf biomass in petiole, mid-rib and lamina, and the differences in chemistry and structure among mid-ribs, petioles and laminas were investigated in 122 species of contrasting leaf size, life form and climatic distribution to determine the extent to which differences in support modify whole-lamina and whole-leaf structural and chemical characteristics, and the extent to which size-dependent support investments are affected by plant life form and site climate. Key Results For the entire data set, leaf fresh mass varied over five orders of magnitude. The percentage of dry mass in mid-rib increased strongly with lamina size, reaching more than 40 % in the largest laminas. The whole-leaf percentage of mid-rib and petiole increased with leaf size, and the overall support investment was more than 60 % in the largest leaves. Fractional support investments were generally larger in herbaceous than in woody species and tended to be lower in Mediterranean than in cool temperate and tropical plants. Mid-ribs and petioles had lower N and C percentages, and lower dry to fresh mass ratio, but greater density (mass per unit volume) than laminas. N percentage of lamina without mid-rib was up to 40 % higher in the largest leaves than the total-lamina (lamina and mid-rib) N percentage, and up to 60 % higher than whole-leaf N percentage, while lamina density calculated without mid-rib was up to 80 % less than that with the mid-rib. For all leaf compartments, N percentage was negatively associated with density and dry to fresh mass ratio, while C percentage was positively linked to these characteristics, reflecting the overall inverse scaling between structural and physiological characteristics. However, the correlations between N and C percentages and structural

  9. Leaf growth pattern in evergreen and deciduous species of the Central Himalaya, India

    NASA Astrophysics Data System (ADS)

    Negi, G. C. S.; Singh, S. P.

    1992-12-01

    Leaf growth patterns were investigated in 11 evergreen (with leaf life-spans of just more than 1 year) and 15 deciduous species, occurring along an elevational gradient of 600-2200 m elevation in the Central Himalaya. Records were made of the leaf initiation period, leaf population dynamics, leaf expansion, leaf mass changes, leaf longevity and related parameters. Species of both groups produced leaves at similar rates during March to April, the driest period of the year. Species of both groups had approximately fully developed foliage during the warm, wet period (mid-June to mid-September) of the monsoon. However, significant differences were found at group level in other characters: shoot length (19.5 cm per shoot for deciduous and 11.7 cm for evergreen species); leaf population per 10 cm shoot length (4.7 vs 15.0); leaf area (107.9 vs 41.4 cm2/ leaf); specific leaf mass (106.9 vs 191.3 g/m2); and leaf mass loss after the monsoon period, being rapid and higher (31.6%) in deciduous species and slow and limited in the evergreens (26.2%). However, species of the two groups showed considerable overlaps in the values of above characters. The evergreen species of the Central Himalaya resembled the deciduous species of the region more than the multi-year leaves of clearly evergreen species. The evergreens bear leaves throughout the year, but like deciduous species bear the cost of annual replacement of old leaves by new leaves. They seem to outcompete deciduous species by producing annually a greater mass of leaves of low-carbon cost (per unit leaf mass), which is capable of conducting photosynthesis all year round. A situation of less marked contrast between favourable and nonfavourable periods, with respect to temperature, seems to favour the leaf characters of the evergreens.

  10. The artificial leaf.

    PubMed

    Nocera, Daniel G

    2012-05-15

    To convert the energy of sunlight into chemical energy, the leaf splits water via the photosynthetic process to produce molecular oxygen and hydrogen, which is in a form of separated protons and electrons. The primary steps of natural photosynthesis involve the absorption of sunlight and its conversion into spatially separated electron-hole pairs. The holes of this wireless current are captured by the oxygen evolving complex (OEC) of photosystem II (PSII) to oxidize water to oxygen. The electrons and protons produced as a byproduct of the OEC reaction are captured by ferrodoxin of photosystem I. With the aid of ferrodoxin-NADP(+) reductase, they are used to produce hydrogen in the form of NADPH. For a synthetic material to realize the solar energy conversion function of the leaf, the light-absorbing material must capture a solar photon to generate a wireless current that is harnessed by catalysts, which drive the four electron/hole fuel-forming water-splitting reaction under benign conditions and under 1 sun (100 mW/cm(2)) illumination. This Account describes the construction of an artificial leaf comprising earth-abundant elements by interfacing a triple junction, amorphous silicon photovoltaic with hydrogen- and oxygen-evolving catalysts made from a ternary alloy (NiMoZn) and a cobalt-phosphate cluster (Co-OEC), respectively. The latter captures the structural and functional attributes of the PSII-OEC. Similar to the PSII-OEC, the Co-OEC self-assembles upon oxidation of an earth-abundant metal ion from 2+ to 3+, may operate in natural water at room temperature, and is self-healing. The Co-OEC also activates H(2)O by a proton-coupled electron transfer mechanism in which the Co-OEC is increased by four hole equivalents akin to the S-state pumping of the Kok cycle of PSII. X-ray absorption spectroscopy studies have established that the Co-OEC is a structural relative of Mn(3)CaO(4)-Mn cubane of the PSII-OEC, where Co replaces Mn and the cubane is extended in a

  11. Role of ethylene in responses of plants to nitrogen availability

    PubMed Central

    Khan, M. I. R.; Trivellini, Alice; Fatma, Mehar; Masood, Asim; Francini, Alessandra; Iqbal, Noushina; Ferrante, Antonio; Khan, Nafees A.

    2015-01-01

    Ethylene is a plant hormone involved in several physiological processes and regulates the plant development during the whole life. Stressful conditions usually activate ethylene biosynthesis and signaling in plants. The availability of nutrients, shortage or excess, influences plant metabolism and ethylene plays an important role in plant adaptation under suboptimal conditions. Among the plant nutrients, the nitrogen (N) is one the most important mineral element required for plant growth and development. The availability of N significantly influences plant metabolism, including ethylene biology. The interaction between ethylene and N affects several physiological processes such as leaf gas exchanges, roots architecture, leaf, fruits, and flowers development. Low plant N use efficiency (NUE) leads to N loss and N deprivation, which affect ethylene biosynthesis and tissues sensitivity, inducing cell damage and ultimately lysis. Plants may respond differently to N availability balancing ethylene production through its signaling network. This review discusses the recent advances in the interaction between N availability and ethylene at whole plant and different organ levels, and explores how N availability induces ethylene biology and plant responses. Exogenously applied ethylene seems to cope the stress conditions and improves plant physiological performance. This can be explained considering the expression of ethylene biosynthesis and signaling genes under different N availability. A greater understanding of the regulation of N by means of ethylene modulation may help to increase NUE and directly influence crop productivity under conditions of limited N availability, leading to positive effects on the environment. Moreover, efforts should be focused on the effect of N deficiency or excess in fruit trees, where ethylene can have detrimental effects especially during postharvest. PMID:26579172

  12. BOREAS TE-5 Leaf Gas Exchange Data

    NASA Technical Reports Server (NTRS)

    Hall, Forrest G. (Editor); Curd, Shelaine (Editor); Ehleriinger, Jim; Brooks, J. Renee; Flanagan, Larry

    2000-01-01

    The BOREAS TE-5 team collected measurements in the NSA and SSA on gas exchange, gas composition, and tree growth. The leaf photosynthetic gas exchange data were collected in the BOREAS NSA and the SSA from 06-Jun- 1994 to 13-Sep- 1994 using a LI-COR 6200 portable photosynthesis system. The data were collected to compare the photosynthetic capacity, stomata] conductance, and leaf intercellular CO, concentrations among the major tree species at the BOREAS sites. The data are average values from diurnal measurements on the upper canopy foliage (sun leaves). The data are available in tabular ASCII files. The data files are available on a CD-ROM (see document number 20010000884), or from the Oak Ridge National Laboratory (ORNL) Distributed Activity Archive Center (DAAC).

  13. Stem hydraulic traits and leaf water-stress tolerance are co-ordinated with the leaf phenology of angiosperm trees in an Asian tropical dry karst forest.

    PubMed

    Fu, Pei-Li; Jiang, Yan-Juan; Wang, Ai-Ying; Brodribb, Tim J; Zhang, Jiao-Lin; Zhu, Shi-Dan; Cao, Kun-Fang

    2012-07-01

    The co-occurring of evergreen and deciduous angiosperm trees in Asian tropical dry forests on karst substrates suggests the existence of different water-use strategies among species. In this study it is hypothesized that the co-occurring evergreen and deciduous trees differ in stem hydraulic traits and leaf water relationships, and there will be correlated evolution in drought tolerance between leaves and stems. A comparison was made of stem hydraulic conductivity, vulnerability curves, wood anatomy, leaf life span, leaf pressure-volume characteristics and photosynthetic capacity of six evergreen and six deciduous tree species co-occurring in a tropical dry karst forest in south-west China. The correlated evolution of leaf and stem traits was examined using both traditional and phylogenetic independent contrasts correlations. It was found that the deciduous trees had higher stem hydraulic efficiency, greater hydraulically weighted vessel diameter (D(h)) and higher mass-based photosynthetic rate (A(m)); while the evergreen species had greater xylem-cavitation resistance, lower leaf turgor-loss point water potential (π(0)) and higher bulk modulus of elasticity. There were evolutionary correlations between leaf life span and stem hydraulic efficiency, A(m), and dry season π(0). Xylem-cavitation resistance was evolutionarily correlated with stem hydraulic efficiency, D(h), as well as dry season π(0). Both wood density and leaf density were closely correlated with leaf water-stress tolerance and A(m). The results reveal the clear distinctions in stem hydraulic traits and leaf water-stress tolerance between the co-occurring evergreen and deciduous angiosperm trees in an Asian dry karst forest. A novel pattern was demonstrated linking leaf longevity with stem hydraulic efficiency and leaf water-stress tolerance. The results show the correlated evolution in drought tolerance between stems and leaves.

  14. Stem hydraulic traits and leaf water-stress tolerance are co-ordinated with the leaf phenology of angiosperm trees in an Asian tropical dry karst forest

    PubMed Central

    Fu, Pei-Li; Jiang, Yan-Juan; Wang, Ai-Ying; Brodribb, Tim J.; Zhang, Jiao-Lin; Zhu, Shi-Dan; Cao, Kun-Fang

    2012-01-01

    Background and Aims The co-occurring of evergreen and deciduous angiosperm trees in Asian tropical dry forests on karst substrates suggests the existence of different water-use strategies among species. In this study it is hypothesized that the co-occurring evergreen and deciduous trees differ in stem hydraulic traits and leaf water relationships, and there will be correlated evolution in drought tolerance between leaves and stems. Methods A comparison was made of stem hydraulic conductivity, vulnerability curves, wood anatomy, leaf life span, leaf pressure–volume characteristics and photosynthetic capacity of six evergreen and six deciduous tree species co-occurring in a tropical dry karst forest in south-west China. The correlated evolution of leaf and stem traits was examined using both traditional and phylogenetic independent contrasts correlations. Key Results It was found that the deciduous trees had higher stem hydraulic efficiency, greater hydraulically weighted vessel diameter (Dh) and higher mass-based photosynthetic rate (Am); while the evergreen species had greater xylem-cavitation resistance, lower leaf turgor-loss point water potential (π0) and higher bulk modulus of elasticity. There were evolutionary correlations between leaf life span and stem hydraulic efficiency, Am, and dry season π0. Xylem-cavitation resistance was evolutionarily correlated with stem hydraulic efficiency, Dh, as well as dry season π0. Both wood density and leaf density were closely correlated with leaf water-stress tolerance and Am. Conclusions The results reveal the clear distinctions in stem hydraulic traits and leaf water-stress tolerance between the co-occurring evergreen and deciduous angiosperm trees in an Asian dry karst forest. A novel pattern was demonstrated linking leaf longevity with stem hydraulic efficiency and leaf water-stress tolerance. The results show the correlated evolution in drought tolerance between stems and leaves. PMID:22585930

  15. Soil water availability and rooting depth as determinants of hydraulic architecture of Patagonian woody species

    Treesearch

    Sandra J. Bucci; Fabian G. Scholz; Guillermo Goldstein; Frederick C. Meinzer; Maria E. Arce

    2009-01-01

    We studied the water economy of nine woody species differing in rooting depth in a Patagonian shrub steppe from southern Argentina to understand how soil water availability and rooting depth determine their hydraulic architecture. Soil water content and potentials, leaf water potentials (Leaf) hydraulic conductivity, wood density (Pw), rooting depth, and specific leaf...

  16. How to pattern a leaf

    USDA-ARS?s Scientific Manuscript database

    Leaf development presents a tremendous resource for tackling the question of patterning in biology. Leaves can be simple or highly dissected. They may have elaborated parts such as the tendrils of a pea leaf or the rolled blade of a carnivorous pitcher plant. Despite the variation in size, shape, an...

  17. Exserohilum Leaf Spot on Tigergrass

    USDA-ARS?s Scientific Manuscript database

    Tigergrass (Thysanolaena maxima (Roxb.) Kuntze ) is a popular ornamental grass grown throughout landscapes in South Florida. In the summer of 2006, a leaf spot was observed on tigergrass in the landscape and a commercial nursery in Homestead, FL. The causal agent of the leaf spot was isolated, cha...

  18. Leaf growth dynamics in four plant species of the Patagonian Monte, Argentina.

    PubMed

    Campanella, M Victoria; Bertiller, Mónica B

    2013-07-01

    Studying plant responses to environmental variables is an elemental key to understand the functioning of arid ecosystems. We selected four dominant species of the two main life forms. The species selected were two evergreen shrubs: Larrea divaricata and Chuquiraga avellanedae and two perennial grasses: Nassella tenuis and Pappostipa speciosa. We registered leaf/shoot growth, leaf production and environmental variables (precipitation, air temperature, and volumetric soil water content at two depths) during summer-autumn and winter-spring periods. Multiple regressions were used to test the predictive power of the environmental variables. During the summer-autumn period, the strongest predictors of leaf/shoot growth and leaf production were the soil water content of the upper layer and air temperature while during the winter-spring period, the strongest predictor was air temperature. In conclusion, we found that the leaf/shoot growth and leaf production were associated with current environmental conditions, specially to soil water content and air temperature.

  19. Spur behaviour in almond trees: relationships between previous year spur leaf area, fruit bearing and mortality.

    PubMed

    Lampinen, Bruce D; Tombesi, Sergio; Metcalf, Samuel G; DeJong, Theodore M

    2011-07-01

    In mature almond (Prunus dulcis) orchards, the majority of crop is borne on spurs (short, proleptic shoots) that can live for several years and can produce from one to five fruits. Previous research has led to the hypothesis that spur longevity is related to spur light exposure, cropping and age. However, limited quantitative data are available to substantiate these hypotheses. The objective of this study was to determine spur characteristics that were most highly correlated with spur productivity and longevity in mature, bearing almond trees. Previous year spur leaf area was strongly related to spur viability and flowering; the greater the leaf area in the previous year, the higher the probability of spur survival into the next year and the higher the probability for the spur to bear one or more flowers. Previous year bearing also appeared to influence viability and return bloom, especially in spurs with low leaf area. These results suggest that spur source-sink balance is basic to the life cycle of almond spurs. Furthermore, the results are consistent with the hypothesis that spurs are semi-autonomous organs with respect to carbohydrate balance for much of the growing season. Finally, this information provides general thresholds for maintaining spur viability and productivity that will be useful for developing and evaluating tree training systems and orchard management practices.

  20. Immobilization and mineralization of N and P by heterotrophic microbes during leaf decomposition

    Treesearch

    Beth Cheever; Erika Kratzer; Jackson Webster

    2012-01-01

    According to theory, the rate and stoichiometry of microbial mineralization depend, in part, on nutrient availability. For microbes associated with leaves in streams, nutrients are available from both the water column and the leaf. Therefore, microbial nutrient cycling may change with nutrient availability and during leaf decomposition. We explored spatial and temporal...

  1. Variations of leaf N, P concentrations in shrubland biomes across northern China: phylogeny, climate and soil

    NASA Astrophysics Data System (ADS)

    Yang, X.; Chi, X.; Ji, C.; Liu, H.; Ma, W.; Mohhammat, A.; Shi, Z.; Wang, X.; Yu, S.; Yue, M.; Tang, Z.

    2015-11-01

    Concentrations of leaf nitrogen (N) and phosphorus (P) are key leaf traits in ecosystem functioning and dynamics. Foliar stoichiometry varies remarkably among life forms. However, previous studies have focused on trees and grasses, leaving the knowledge gap for the stoichiometric patterns of shrubs. In this study, we explored the intra- and interspecific variations of leaf N and P concentration in relation to climate, soil property and evolutionary history based on 1486 samples composed of 163 shrub species from 361 shrubland sites in northern China expanding 46.1° (86.7-132.8° E) in longitude and 19.8° (32.6-52.4° N) in latitude. The results showed that leaf N concentration decreased with precipitation, leaf P concentration decreased with temperature and increased with precipitation and soil P concentration. Both leaf N and P concentrations were phylogenetically conserved, but leaf P concentration was less conserved than leaf N concentration. At community level, climates explained more interspecific, while soil nutrient explained more intraspecific, variation of leaf nutrient concentrations. These results suggested that leaf N and P concentrations responded to climate, soil, and phylogeny in different ways. Climate influenced the community chemical traits through the shift in species composition, whereas soil directly influenced the community chemical traits.

  2. Biomechanical and leaf-climate relationships: a comparison of ferns and seed plants.

    PubMed

    Peppe, Daniel J; Lemons, Casee R; Royer, Dana L; Wing, Scott L; Wright, Ian J; Lusk, Christopher H; Rhoden, Chazelle H

    2014-02-01

    Relationships of leaf size and shape (physiognomy) with climate have been well characterized for woody non-monocotyledonous angiosperms (dicots), allowing the development of models for estimating paleoclimate from fossil leaves. More recently, petiole width of seed plants has been shown to scale closely with leaf mass. By measuring petiole width and leaf area in fossils, leaf mass per area (MA) can be estimated and an approximate leaf life span inferred. However, little is known about these relationships in ferns, a clade with a deep fossil record and with the potential to greatly expand the applicability of these proxies. We measured the petiole width, MA, and leaf physiognomic characters of 179 fern species from 188 locations across six continents. We applied biomechanical models and assessed the relationship between leaf physiognomy and climate using correlational approaches. The scaling relationship between area-normalized petiole width and MA differs between fern fronds and pinnae. The scaling relationship is best modeled as an end-loaded cantilevered beam, which is different from the best-fit biomechanical model for seed plants. Fern leaf physiognomy is not influenced by climatic conditions. The cantilever beam model can be applied to fossil ferns. The lack of sensitivity of leaf physiognomy to climate in ferns argues against their use to reconstruct paleoclimate. Differences in climate sensitivity and biomechanical relationships between ferns and seed plants may be driven by differences in their hydraulic conductivity and/or their differing evolutionary histories of vein architecture and leaf morphology.

  3. Antibacterial, Antibiofilm Effect of Burdock (Arctium lappa L.) Leaf Fraction and Its Efficiency in Meat Preservation.

    PubMed

    Lou, Zaixiang; Li, Cheng; Kou, Xingran; Yu, Fuhao; Wang, Hongxin; Smith, Gary M; Zhu, Song

    2016-08-01

    First, the antibacterial, antibiofilm effect and chemical composition of burdock (Arctium lappa L.) leaf fractions were studied. Then, the efficiency of burdock leaf fractions in pork preservation was evaluated. The results showed that burdock leaf fraction significantly inhibited the growth and biofilm development of Escherichia coli and Salmonella Typhimurium. MICs of burdock leaf fractions on E. coli and Salmonella Typhimurium were both 2 mg/ml. At a concentration of 2.0 mg/ml, the inhibition rates of the fraction on growth and development of E. coli and Salmonella Typhimurium biofilms were 78.7 and 69.9%, respectively. During storage, the log CFU per gram of meat samples treated with burdock leaf fractions decreased 2.15, compared with the samples without treatment. The shelf life of pork treated with burdock leaf fractions was extended 6 days compared with the pork without treatment, and the sensory property was obviously improved. Compared with the control group, burdock leaf fraction treatment significantly decreased the total volatile basic nitrogen value and pH of the meat samples. Chemical composition analysis showed that the burdock leaf fraction consisted of chlorogenic acid, caffeic acid, p-coumaric acid, rutin, cynarin, crocin, luteolin, arctiin, and quercetin. As a vegetable with an abundant source, burdock leaf is safe, affordable, and efficient in meat preservation, indicating that burdock leaf fraction is a promising natural preservative for pork.

  4. Predicting leaf traits of herbaceous species from their spectral characteristics

    PubMed Central

    Roelofsen, Hans D; van Bodegom, Peter M; Kooistra, Lammert; Witte, Jan-Philip M

    2014-01-01

    Trait predictions from leaf spectral properties are mainly applied to tree species, while herbaceous systems received little attention in this topic. Whether similar trait–spectrum relations can be derived for herbaceous plants that differ strongly in growing strategy and environmental constraints is therefore unknown. We used partial least squares regression to relate key traits to leaf spectra (reflectance, transmittance, and absorbance) for 35 herbaceous species, sampled from a wide range of environmental conditions. Specific Leaf Area and nutrient-related traits (N and P content) were poorly predicted from any spectrum, although N prediction improved when expressed on a per area basis (mg/m2 leaf surface) instead of mass basis (mg/g dry matter). Leaf dry matter content was moderately to good correlated with spectra. We explain our results by the range of environmental constraints encountered by herbaceous species; both N and P limitations as well as a range of light and water availabilities occurred. This weakened the relation between the measured response traits and the leaf constituents that are truly responsible for leaf spectral behavior. Indeed, N predictions improve considering solely upper or under canopy species. Therefore, trait predictions in herbaceous systems should focus on traits relating to dry matter content and the true, underlying drivers of spectral properties. PMID:24683454

  5. Predicting leaf traits of herbaceous species from their spectral characteristics.

    PubMed

    Roelofsen, Hans D; van Bodegom, Peter M; Kooistra, Lammert; Witte, Jan-Philip M

    2014-03-01

    Trait predictions from leaf spectral properties are mainly applied to tree species, while herbaceous systems received little attention in this topic. Whether similar trait-spectrum relations can be derived for herbaceous plants that differ strongly in growing strategy and environmental constraints is therefore unknown. We used partial least squares regression to relate key traits to leaf spectra (reflectance, transmittance, and absorbance) for 35 herbaceous species, sampled from a wide range of environmental conditions. Specific Leaf Area and nutrient-related traits (N and P content) were poorly predicted from any spectrum, although N prediction improved when expressed on a per area basis (mg/m(2) leaf surface) instead of mass basis (mg/g dry matter). Leaf dry matter content was moderately to good correlated with spectra. We explain our results by the range of environmental constraints encountered by herbaceous species; both N and P limitations as well as a range of light and water availabilities occurred. This weakened the relation between the measured response traits and the leaf constituents that are truly responsible for leaf spectral behavior. Indeed, N predictions improve considering solely upper or under canopy species. Therefore, trait predictions in herbaceous systems should focus on traits relating to dry matter content and the true, underlying drivers of spectral properties.

  6. Effect of a single amino acid substitution in the NLS domain of Tomato yellow leaf curl virus-Israel (TYLCV-IL) capsid protein (CP) on its activity and on the virus life cycle.

    PubMed

    Yaakov, Noga; Levy, Yael; Belausov, Eduard; Gaba, Victor; Lapidot, Moshe; Gafni, Yedidya

    2011-06-01

    The capsid protein (CP) of Tomato yellow leaf curl virus-Israel (TYLCV-IL), encoded by the v1 gene, is the only known component of the viral capsid. Three point mutations introduced into the conserved NLS region of the CP were investigated. One mutant, in which the Arg at position 19 was converted to Leu, had the most significant effect on the CP-CP homotypic interaction as well as on CP's interaction with its nuclear receptor karyopherin α1 and with the protein GroEL. The latter has been suggested to protect the virions in the insect vector hemolymph. These effects were first observed by yeast two-hybrid assay and then confirmed in tobacco protoplasts by measuring fluorescence resonance energy transfer (FRET) between YFP- and CFP-tagged proteins. Most importantly, when the point mutation converting Arg 19 to Leu was introduced into the full-length TYLCV genome, it disrupted its ability to cause symptoms.

  7. C:N:P Stoichiometry and Leaf Traits of Halophytes in an Arid Saline Environment, Northwest China

    PubMed Central

    Wang, Lilong; Zhao, Guanxiang; Li, Meng; Zhang, Mingting; Zhang, Lifang; Zhang, Xinfang; An, Lizhe; Xu, Shijian

    2015-01-01

    Salinization is an important and increasingly prevalent issue which has broad and profound effects on plant survival and distribution pattern. To understand the patterns and potential drivers of leaf traits in saline environments, we determined the soil properties, leaf morphological traits (specific leaf area, SLA, and leaf dry matter content, LDMC), leaf chemical traits (leaf carbon, C, nitrogen, N, and phosphorus, P, stoichiometry) based on 142 observations collected from 23 sites in an arid saline environment, which is a vulnerable ecosystem in northwest China. We also explored the relationships among leaf traits, the responses of leaf traits, and plant functional groups (herb, woody, and succulent woody) to various saline environments. The arid desert halophytes were characterized by lower leaf C and SLA levels, higher N, but stable P and N:P. The leaf morphological traits were correlated significantly with the C, N, and P contents across all observations, but they differed within each functional group. Succulent woody plants had the lowest leaf C and highest leaf N levels among the three functional groups. The growth of halophytes might be more limited by N rather than P in the study area. GLM analysis demonstrated that the soil available nutrients and plant functional groups, but not salinity, were potential drivers of leaf C:N:P stoichiometry in halophytes, whereas species differences accounted for the largest contributions to leaf morphological variations. Our study provides baseline information to facilitate the management and restoration of arid saline desert ecosystem. PMID:25798853

  8. Scaling up stomatal conductance from leaf to canopy using a dual-leaf model for estimating crop evapotranspiration.

    PubMed

    Ding, Risheng; Kang, Shaozhong; Du, Taisheng; Hao, Xinmei; Zhang, Yanqun

    2014-01-01

    The dual-source Shuttleworth-Wallace model has been widely used to estimate and partition crop evapotranspiration (λET). Canopy stomatal conductance (Gsc), an essential parameter of the model, is often calculated by scaling up leaf stomatal conductance, considering the canopy as one single leaf in a so-called "big-leaf" model. However, Gsc can be overestimated or underestimated depending on leaf area index level in the big-leaf model, due to a non-linear stomatal response to light. A dual-leaf model, scaling up Gsc from leaf to canopy, was developed in this study. The non-linear stomata-light relationship was incorporated by dividing the canopy into sunlit and shaded fractions and calculating each fraction separately according to absorbed irradiances. The model includes: (1) the absorbed irradiance, determined by separately integrating the sunlit and shaded leaves with consideration of both beam and diffuse radiation; (2) leaf area for the sunlit and shaded fractions; and (3) a leaf conductance model that accounts for the response of stomata to PAR, vapor pressure deficit and available soil water. In contrast to the significant errors of Gsc in the big-leaf model, the predicted Gsc using the dual-leaf model had a high degree of data-model agreement; the slope of the linear regression between daytime predictions and measurements was 1.01 (R2 = 0.98), with RMSE of 0.6120 mm s-1 for four clear-sky days in different growth stages. The estimates of half-hourly λET using the dual-source dual-leaf model (DSDL) agreed well with measurements and the error was within 5% during two growing seasons of maize with differing hydrometeorological and management strategies. Moreover, the estimates of soil evaporation using the DSDL model closely matched actual measurements. Our results indicate that the DSDL model can produce more accurate estimation of Gsc and λET, compared to the big-leaf model, and thus is an effective alternative approach for estimating and partitioning λET.

  9. Does investment in leaf defenses drive changes in leaf economic strategy? A focus on whole-plant ontogeny.

    PubMed

    Mason, Chase M; Donovan, Lisa A

    2015-04-01

    Leaf defenses have long been studied in the context of plant growth rate, resource availability, and optimal investment theory. Likewise, one of the central modern paradigms of plant ecophysiology, the leaf economics spectrum (LES), has been extensively studied in the context of these factors across ecological scales ranging from global species data sets to temporal shifts within individuals. Despite strong physiological links between LES strategy and leaf defenses in structure, function, and resource investment, the relationship between these trait classes has not been well explored. This study investigates the relationship between leaf defenses and LES strategy across whole-plant ontogeny in three diverse Helianthus species known to exhibit dramatic ontogenetic shifts in LES strategy, focusing primarily on physical and quantitative chemical defenses. Plants were grown under controlled environmental conditions and sampled for LES and defense traits at four ontogenetic stages. Defenses were found to shift strongly with ontogeny, and to correlate strongly with LES strategy. More advanced ontogenetic stages with more conservative LES strategy leaves had higher tannin activity and toughness in all species, and higher leaf dry matter content in two of three species. Modeling results in two species support the conclusion that changes in defenses drive changes in LES strategy through ontogeny, and in one species that changes in defenses and LES strategy are likely independently driven by ontogeny. Results of this study support the hypothesis that leaf-level allocation to defenses might be an important determinant of leaf economic traits, where high investment in defenses drives a conservative LES strategy.

  10. Leaf extraction and analysis framework graphical user interface: segmenting and analyzing the structure of leaf veins and areoles.

    PubMed

    Price, Charles A; Symonova, Olga; Mileyko, Yuriy; Hilley, Troy; Weitz, Joshua S

    2011-01-01

    Interest in the structure and function of physical biological networks has spurred the development of a number of theoretical models that predict optimal network structures across a broad array of taxonomic groups, from mammals to plants. In many cases, direct tests of predicted network structure are impossible given the lack of suitable empirical methods to quantify physical network geometry with sufficient scope and resolution. There is a long history of empirical methods to quantify the network structure of plants, from roots, to xylem networks in shoots and within leaves. However, with few exceptions, current methods emphasize the analysis of portions of, rather than entire networks. Here, we introduce the Leaf Extraction and Analysis Framework Graphical User Interface (LEAF GUI), a user-assisted software tool that facilitates improved empirical understanding of leaf network structure. LEAF GUI takes images of leaves where veins have been enhanced relative to the background, and following a series of interactive thresholding and cleaning steps, returns a suite of statistics and information on the structure of leaf venation networks and areoles. Metrics include the dimensions, position, and connectivity of all network veins, and the dimensions, shape, and position of the areoles they surround. Available for free download, the LEAF GUI software promises to facilitate improved understanding of the adaptive and ecological significance of leaf vein network structure.

  11. Remote sensing of leaf N to improve carbon assimilation prediction

    NASA Astrophysics Data System (ADS)

    Loozen, Yasmina; Rebel, Karin; Karssenberg, Derek; de Jong, Steven; Wassen, Martin

    2016-04-01

    Predicting and understanding carbon assimilation by terrestrial vegetation remains fundamental in the context of climate change. Carbon and nitrogen cycles are linked as nitrogen is an essential nutrient for plant growth. In this respect the N cycle is integrated into vegetation models predicting vegetation carbon uptake. However plant traits within the N cycle, such as leaf nitrogen, are lacking at large scales, which complicates the calibration and optimization of the N cycling modelling modules. Remote sensing techniques could offer the possibility to detect leaf N concentration at continental scales. In fact, it has already been used to sense leaf N at local, e.g. in agricultural oriented applications, as well as at regional scales. The objective of this study is to enhance the availability of leaf N estimates in forested ecosystems at European scale using remote sensing products. European forest leaf N data were obtained from the TRY database. The MERIS Terrestrial chlorophyll Index (MTCI) Level 3 product as well as two reflectance bands in the NIR region (band centers at 865 and 885nm) both from MERIS aboard ENVISAT (ESA) were used to study statistical relationship with leaf N data. In a first step, we analyzed 1892 Catalonian (NE Spain) forest plots using a linear regression method. The regressions results between leaf N and either MTCI or NIR bands were significant (p< 0.001). The R-square for the regression between leaf N and MTCI was equal to 0.13. The method performed better for broadleaves deciduous plots (R-square = 0.11) than for needleleaves or broadleaves evergreen plots. The relationship between leaf N and MTCI was also higher for the plots sampled during summer (R-square = 0.28 in July) than for the plots sampled during the rest of the year. In a second step the method will be applied on and will include more diverse forest types at the European level.

  12. Light acclimation optimizes leaf functional traits despite height-related constraints in a canopy shading experiment.

    PubMed

    Coble, Adam P; Cavaleri, Molly A

    2015-04-01

    Within-canopy gradients of leaf functional traits have been linked to both light availability and vertical gradients in leaf water potential. While observational studies can reveal patterns in leaf traits, within-canopy experimental manipulations can provide mechanistic insight to tease apart multiple interacting drivers. Our objectives were to disentangle effects of height and light environment on leaf functional traits by experimentally shading branches along vertical gradients within a sugar maple (Acer saccharum) forest. Shading reduced leaf mass per area (LMA), leaf density, area-based leaf nitrogen (N(area)), and carbon:nitrogen (C:N) ratio, and increased mass-based leaf nitrogen (N(mass)), highlighting the importance of light availability on leaf morphology and chemistry. Early in the growing season, midday leaf water potential (Ψ(mid)), LMA, and N(area) were driven primarily by height; later in the growing season, light became the most important driver for LMA and Narea. Carbon isotope composition (δ(13)C) displayed strong, linear correlations with height throughout the growing season, but did not change with shading, implying that height is more influential than light on water use efficiency and stomatal behavior. LMA, leaf density, N(mass), C:N ratio, and δ(13)C all changed seasonally, suggesting that leaf ageing effects on leaf functional traits are equally as important as microclimatic conditions. Overall, our results indicate that: (1) stomatal sensitivity to vapor pressure deficit or Ψ(mid) constrains the supply of CO2 to leaves at higher heights, independent of light environment, and (2) LMA and N(area) distributions become functionally optimized through morphological acclimation to light with increasing leaf age despite height-related constraints.

  13. Leaf hydraulics II: vascularized tissues.

    PubMed

    Rockwell, Fulton E; Holbrook, N Michele; Stroock, Abraham D

    2014-01-07

    Current models of leaf hydration employ an Ohm's law analogy of the leaf as an ideal capacitor, neglecting the resistance to flow between cells, or treat the leaf as a plane sheet with a source of water at fixed potential filling the mid-plane, neglecting the discrete placement of veins as well as their resistance. We develop a model of leaf hydration that considers the average conductance of the vascular network to a representative areole (region bounded by the vascular network), and represent the volume of tissue within the areole as a poroelastic composite of cells and air spaces. Solutions to the 3D flow problem are found by numerical simulation, and these results are then compared to 1D models with exact solutions for a range of leaf geometries, based on a survey of temperate woody plants. We then show that the hydration times given by these solutions are well approximated by a sum of the ideal capacitor and plane sheet times, representing the time for transport through the vasculature and tissue respectively. We then develop scaling factors relating this approximate solution to the 3D model, and examine the dependence of these scaling factors on leaf geometry. Finally, we apply a similar strategy to reduce the dimensions of the steady state problem, in the context of peristomatal transpiration, and consider the relation of transpirational gradients to equilibrium leaf water potential measurements. © 2013 Published by Elsevier Ltd. All rights reserved.

  14. Decline of photosynthetic capacity with leaf age and position in two tropical pioneer tree species.

    PubMed

    Kitajima, Kaoru; Mulkey, Stephen S; Samaniego, Mirna; Joseph Wright, S

    2002-12-01

    The effect of leaf age on photosynthetic capacity, a critical parameter in the theory of optimal leaf longevity, was studied for two tropical pioneer tree species, Cecropia longipes and Urera caracasana, in a seasonally dry forest in Panama. These species continuously produce short-lived leaves (74 and 93 d, respectively) during the rainy season (May-December) on orthotropic branches. However, they differ in leaf production rate, maximum number of leaves per branch, light environment experienced by the leaves, leaf mass per unit area, and nitrogen content. Light-saturated photosynthetic rates for marked leaves of known ages (±1 wk) were measured with two contrasting schemes (repeated measurements vs. chronosequence within branch), which overall produced similar results. In both species, photosynthetic rates and nitrogen use efficiency were negatively correlated with leaf age and positively correlated with light availability. Photosynthetic rates declined faster with leaf age in Cecropia than in Urera as predicted by the theory. The rate of decline was faster for leaves on branches with faster leaf turnover rates. Nitrogen per unit leaf area decreased with leaf age only for Urera. Leaf mass per unit area increased with leaf age, either partly (in Cecropia) or entirely (in Urera) due to ash accumulation.

  15. VOC Emissions From Decomposing Leaf Litter

    NASA Astrophysics Data System (ADS)

    Brown, E. M.; Wilkinson, M. J.; Fierer, N.; Monson, R. K.

    2007-12-01

    The emission of VOCs from the biosphere has a profound effect on the oxidative capacity of the troposphere. Most studies of the flux of reactive carbon from the biosphere have focused on BVOC emissions at leaf and canopy scales with relatively few studies investigating BVOC emissions from soils. Here we present results describing the emissions of a suite of BVOCs from different litter types under different levels of nitrogen availability. To investigate these effects, three biochemically distinct litter types (Deschampsia sp., Acomostylis sp., and Rhododendron sp.) were coarsely ground and incubated in the dark for two months under different nitrogen regimes at optimal conditions for microbial activity. We used proton transfer reaction mass spectrometry and an infrared gas analyzer (IRGA) to monitor BVOC emissions and CO2 production rates throughout the course of the investigation. When different leaf litter types decomposed, they released distinctly different types and quantities of VOCs. However, varying nitrogen availability caused the VOC signature from some litters to change dramatically. We suggest that decomposition of leaf litter could provide a substantive source of reactive carbon to the atmosphere at local and regional scales and hypothesize that nitrogen deposition may play a role in attenuating the release of some reactive species.

  16. BOREAS TE-5 Leaf Carbon Isotope Data

    NASA Technical Reports Server (NTRS)

    Hall, Forrest G. (Editor); Curd, Shelaine (Editor); Ehleriinger, Jim; Brooks, J. Renee; Flanagan, Larry

    2000-01-01

    The BOREAS TE-5 team collected measurements in the NSA and SSA on gas exchange, gas composition, and tree growth. This documentation describes leaf carbon isotope data that were collected in 1993 and 1994 at the NSA and SSA OJP sites, the SSA OBS site, and the NSA UBS site. In addition, leaf carbon isotope data were collected in 1994 only at the NSA and SSA OA sites. These data was collected to provide seasonal integrated physiological information for 10 to 15 common species at these 6 BOREAS sites. The data are stored in tabular ASCII files. The data files are available on a CD-ROM (see document number 20010000884), or from the Oak Ridge National Laboratory (ORNL) Distributed Active Archive Center (DAAC).

  17. Maize YABBY genes drooping leaf1 and drooping leaf2 affect agronomic traits by regulating leaf architecture

    USDA-ARS?s Scientific Manuscript database

    Leaf architectural traits, such as length, width and angle, directly influence canopy structure and light penetration, photosynthate production and overall yield. We discovered and characterized a maize (Zea mays) mutant with aberrant leaf architecture we named drooping leaf1 (drl1), as leaf blades ...

  18. Active suppression of a leaf meristem orchestrates determinate leaf growth.

    PubMed

    Alvarez, John Paul; Furumizu, Chihiro; Efroni, Idan; Eshed, Yuval; Bowman, John L

    2016-10-06

    Leaves are flat determinate organs derived from indeterminate shoot apical meristems. The presence of a specific leaf meristem is debated, as anatomical features typical of meristems are not present in leaves. Here we demonstrate that multiple NGATHA (NGA) and CINCINNATA-class-TCP (CIN-TCP) transcription factors act redundantly, shortly after leaf initiation, to gradually restrict the activity of a leaf meristem in Arabidopsis thaliana to marginal and basal domains, and that their absence confers persistent marginal growth to leaves, cotyledons and floral organs. Following primordia initiation, the restriction of the broadly acting leaf meristem to the margins is mediated by the juxtaposition of adaxial and abaxial domains and maintained by WOX homeobox transcription factors, whereas other marginal elaboration genes are dispensable for its maintenance. This genetic framework parallels the morphogenetic program of shoot apical meristems and may represent a relic of an ancestral shoot system from which seed plant leaves evolved.

  19. Leaf Relative Water Content Estimated from Leaf Reflectance and Transmittance

    NASA Technical Reports Server (NTRS)

    Vanderbilt, Vern; Daughtry, Craig; Dahlgren, Robert

    2016-01-01

    Remotely sensing the water status of plants and the water content of canopies remain long term goals of remote sensing research. In the research we report here, we used optical polarization techniques to monitor the light reflected from the leaf interior, R, as well as the leaf transmittance, T, as the relative water content (RWC) of corn (Zea mays) leaves decreased. Our results show that R and T both change nonlinearly. The result show that the nonlinearities cancel in the ratio R/T, which appears linearly related to RWC for RWC less than 90%. The results suggest that potentially leaf water status and perhaps even canopy water status could be monitored starting from leaf and canopy optical measurements.

  20. Leaf chlorophyll content as a proxy for leaf photosynthetic capacity.

    PubMed

    Croft, Holly; Chen, Jing M; Luo, Xiangzhong; Bartlett, Paul; Chen, Bin; Staebler, Ralf M

    2017-09-01

    Improving the accuracy of estimates of forest carbon exchange is a central priority for understanding ecosystem response to increased atmospheric CO2 levels and improving carbon cycle modelling. However, the spatially continuous parameterization of photosynthetic capacity (Vcmax) at global scales and appropriate temporal intervals within terrestrial biosphere models (TBMs) remains unresolved. This research investigates the use of biochemical parameters for modelling leaf photosynthetic capacity within a deciduous forest. Particular attention is given to the impacts of seasonality on both leaf biophysical variables and physiological processes, and their interdependent relationships. Four deciduous tree species were sampled across three growing seasons (2013-2015), approximately every 10 days for leaf chlorophyll content (ChlLeaf ) and canopy structure. Leaf nitrogen (NArea ) was also measured during 2014. Leaf photosynthesis was measured during 2014-2015 using a Li-6400 gas-exchange system, with A-Ci curves to model Vcmax. Results showed that seasonality and variations between species resulted in weak relationships between Vcmax normalized to 25°C (Vcmax25) and NArea (R(2)  = 0.62, P < 0.001), whereas ChlLeaf demonstrated a much stronger correlation with Vcmax25 (R(2)  = 0.78, P < 0.001). The relationship between ChlLeaf and NArea was also weak (R(2)  = 0.47, P < 0.001), possibly due to the dynamic partitioning of nitrogen, between and within photosynthetic and nonphotosynthetic fractions. The spatial and temporal variability of Vcmax25 was mapped using Landsat TM/ETM satellite data across the forest site, using physical models to derive ChlLeaf . TBMs largely treat photosynthetic parameters as either fixed constants or varying according to leaf nitrogen content. This research challenges assumptions that simple NArea -Vcmax25 relationships can reliably be used to constrain photosynthetic capacity in TBMs, even within the same plant functional type. It

  1. Leaf fall as a source of leaf miner mortality.

    PubMed

    Pritchard, I M; James, R

    1984-09-01

    Leaf miner deaths resulting from the death of their leaves were assessd by collecting falling leaves of holm oak and beech. The Phyllonorycter mines thus captured were examined to ascertain the cause of death. For both mining species the mortality from leaf shedding accounted for less than 2.8% of the mining cohorts. It is argued that the level of mortality is insufficient for population regulation, as has been previously suggested.

  2. 7 CFR 29.3036 - Leaf surface.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 7 Agriculture 2 2014-01-01 2014-01-01 false Leaf surface. 29.3036 Section 29.3036 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing... Leaf surface. The smoothness or roughness of the web or lamina of a tobacco leaf. Leaf surface is...

  3. 7 CFR 29.3036 - Leaf surface.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Leaf surface. 29.3036 Section 29.3036 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing... Leaf surface. The smoothness or roughness of the web or lamina of a tobacco leaf. Leaf surface is...

  4. Diffuse and specular characteristics of leaf reflectance

    NASA Technical Reports Server (NTRS)

    Grant, Lois

    1987-01-01

    In this paper, the evolution of current understanding of the mechanisms of leaf reflectance is reviewed. The use of measurements of polarized reflectance to separate leaf reflectance into diffuse and specular components is discussed. A section on the factors influencing leaf reflectance - leaf structure and physiological disturbances - is included along with discussion on the manner in which these influences are manifested.

  5. 7 CFR 29.3036 - Leaf surface.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 7 Agriculture 2 2012-01-01 2012-01-01 false Leaf surface. 29.3036 Section 29.3036 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing... Leaf surface. The smoothness or roughness of the web or lamina of a tobacco leaf. Leaf surface is...

  6. 7 CFR 29.3036 - Leaf surface.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 7 Agriculture 2 2011-01-01 2011-01-01 false Leaf surface. 29.3036 Section 29.3036 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing... Leaf surface. The smoothness or roughness of the web or lamina of a tobacco leaf. Leaf surface is...

  7. 7 CFR 29.3036 - Leaf surface.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 7 Agriculture 2 2013-01-01 2013-01-01 false Leaf surface. 29.3036 Section 29.3036 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing... Leaf surface. The smoothness or roughness of the web or lamina of a tobacco leaf. Leaf surface is...

  8. Experiments in Whole Leaf Photosynthesis

    ERIC Educational Resources Information Center

    Stewart, J. C.; And Others

    1974-01-01

    Described is a simple experimental system, which uses radioactive carbon dioxide to study whole leaf photosynthesis under a variety of conditions. Other experiments and simple apparatus for the experiments are also described. (Author/RH)

  9. Near infrared leaf reflectance modeling

    NASA Technical Reports Server (NTRS)

    Parrish, J. B.

    1985-01-01

    Near infrared leaf reflectance modeling using Fresnel's equation (Kumar and Silva, 1973) and Snell's Law successfully approximated the spectral curve for a 0.25-mm turgid oak leaf lying on a Halon background. Calculations were made for ten interfaces, air-wax, wax-cellulose, cellulose-water, cellulose-air, air-water, and their inverses. A water path of 0.5 mm yielded acceptable results, and it was found that assignment of more weight to those interfaces involving air versus water or cellulose, and less to those involving wax, decreased the standard deviation of the error for all wavelengths. Data suggest that the air-cell interface is not the only important contributor to the overall reflectance of a leaf. Results also argue against the assertion that the near infrared plateau is a function of cell structure within the leaf.

  10. Hormonal Regulation of Leaf Abscission

    PubMed Central

    Jacobs, William P.

    1968-01-01

    A review is given of the progress made during the last 6 years in elucidating the nature, locus of action, and transport properties of the endogenous hormones that control leaf abscission. PMID:16657014

  11. Experiments in Whole Leaf Photosynthesis

    ERIC Educational Resources Information Center

    Stewart, J. C.; And Others

    1974-01-01

    Described is a simple experimental system, which uses radioactive carbon dioxide to study whole leaf photosynthesis under a variety of conditions. Other experiments and simple apparatus for the experiments are also described. (Author/RH)

  12. Scaling Up Stomatal Conductance from Leaf to Canopy Using a Dual-Leaf Model for Estimating Crop Evapotranspiration

    PubMed Central

    Ding, Risheng; Kang, Shaozhong; Du, Taisheng; Hao, Xinmei; Zhang, Yanqun

    2014-01-01

    The dual-source Shuttleworth-Wallace model has been widely used to estimate and partition crop evapotranspiration (λET). Canopy stomatal conductance (Gsc), an essential parameter of the model, is often calculated by scaling up leaf stomatal conductance, considering the canopy as one single leaf in a so-called “big-leaf” model. However, Gsc can be overestimated or underestimated depending on leaf area index level in the big-leaf model, due to a non-linear stomatal response to light. A dual-leaf model, scaling up Gsc from leaf to canopy, was developed in this study. The non-linear stomata-light relationship was incorporated by dividing the canopy into sunlit and shaded fractions and calculating each fraction separately according to absorbed irradiances. The model includes: (1) the absorbed irradiance, determined by separately integrating the sunlit and shaded leaves with consideration of both beam and diffuse radiation; (2) leaf area for the sunlit and shaded fractions; and (3) a leaf conductance model that accounts for the response of stomata to PAR, vapor pressure deficit and available soil water. In contrast to the significant errors of Gsc in the big-leaf model, the predicted Gsc using the dual-leaf model had a high degree of data-model agreement; the slope of the linear regression between daytime predictions and measurements was 1.01 (R2 = 0.98), with RMSE of 0.6120 mm s−1 for four clear-sky days in different growth stages. The estimates of half-hourly λET using the dual-source dual-leaf model (DSDL) agreed well with measurements and the error was within 5% during two growing seasons of maize with differing hydrometeorological and management strategies. Moreover, the estimates of soil evaporation using the DSDL model closely matched actual measurements. Our results indicate that the DSDL model can produce more accurate estimation of Gsc and λET, compared to the big-leaf model, and thus is an effective alternative approach for estimating and

  13. Increasing leaf hydraulic conductance with transpiration rate minimizes the water potential drawdown from stem to leaf.

    PubMed

    Simonin, Kevin A; Burns, Emily; Choat, Brendan; Barbour, Margaret M; Dawson, Todd E; Franks, Peter J

    2015-03-01

    Leaf hydraulic conductance (k leaf) is a central element in the regulation of leaf water balance but the properties of k leaf remain uncertain. Here, the evidence for the following two models for k leaf in well-hydrated plants is evaluated: (i) k leaf is constant or (ii) k leaf increases as transpiration rate (E) increases. The difference between stem and leaf water potential (ΔΨstem-leaf), stomatal conductance (g s), k leaf, and E over a diurnal cycle for three angiosperm and gymnosperm tree species growing in a common garden, and for Helianthus annuus plants grown under sub-ambient, ambient, and elevated atmospheric CO₂ concentration were evaluated. Results show that for well-watered plants k leaf is positively dependent on E. Here, this property is termed the dynamic conductance, k leaf(E), which incorporates the inherent k leaf at zero E, which is distinguished as the static conductance, k leaf(0). Growth under different CO₂ concentrations maintained the same relationship between k leaf and E, resulting in similar k leaf(0), while operating along different regions of the curve owing to the influence of CO₂ on g s. The positive relationship between k leaf and E minimized variation in ΔΨstem-leaf. This enables leaves to minimize variation in Ψleaf and maximize g s and CO₂ assimilation rate over the diurnal course of evaporative demand.

  14. Increasing leaf hydraulic conductance with transpiration rate minimizes the water potential drawdown from stem to leaf

    PubMed Central

    Simonin, Kevin A.; Burns, Emily; Choat, Brendan; Barbour, Margaret M.; Dawson, Todd E.; Franks, Peter J.

    2015-01-01

    Leaf hydraulic conductance (k leaf) is a central element in the regulation of leaf water balance but the properties of k leaf remain uncertain. Here, the evidence for the following two models for k leaf in well-hydrated plants is evaluated: (i) k leaf is constant or (ii) k leaf increases as transpiration rate (E) increases. The difference between stem and leaf water potential (ΔΨstem–leaf), stomatal conductance (g s), k leaf, and E over a diurnal cycle for three angiosperm and gymnosperm tree species growing in a common garden, and for Helianthus annuus plants grown under sub-ambient, ambient, and elevated atmospheric CO2 concentration were evaluated. Results show that for well-watered plants k leaf is positively dependent on E. Here, this property is termed the dynamic conductance, k leaf(E), which incorporates the inherent k leaf at zero E, which is distinguished as the static conductance, k leaf(0). Growth under different CO2 concentrations maintained the same relationship between k leaf and E, resulting in similar k leaf(0), while operating along different regions of the curve owing to the influence of CO2 on g s. The positive relationship between k leaf and E minimized variation in ΔΨstem–leaf. This enables leaves to minimize variation in Ψleaf and maximize g s and CO2 assimilation rate over the diurnal course of evaporative demand. PMID:25547915

  15. Leaf nitrogen distribution in relation to crown architecture in the tall canopy species, Fagus crenata.

    PubMed

    Osada, Noriyuki; Yasumura, Yuko; Ishida, Atsushi

    2014-08-01

    The theory of optimal leaf N distribution predicts that the C gain of plants is maximized when the N content per unit area (N(area)) scales with light availability, but most previous studies have demonstrated that the N distribution is not proportional to light availability. In tall trees, the leaves are often clustered on twigs (leaf cluster) and not evenly distributed within the crowns. Thus, we hypothesized that the suboptimal N distribution is partly caused by the limited capacity to translocate N between leaf clusters, and consequently, the relationship between light and N(area) differs for leaves in different clusters. We investigated the light availability and N content of all individual leaves within several leaf clusters on tall trees of a deciduous canopy species Fagus crenata in Japan. We observed that the within-cluster leaf N distribution patterns differed from the between-cluster patterns and the slopes of the relationships between light and N(area) were lower within clusters than between clusters. According to the detailed analysis of the N distribution within leaf clusters, N(area) was greater for current-year shoots with greater light availability or a larger total leaf area. The latter pattern was probably caused by the greater sink strength of the current-year shoots with a larger leaf area. These N distribution patterns suggest that leaf clusters are fairly independent with respect to their N use, and the productivity of real F. crenata crowns may be less than optimal.

  16. 7 CFR 29.2528 - Leaf.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 7 Agriculture 2 2012-01-01 2012-01-01 false Leaf. 29.2528 Section 29.2528 Agriculture Regulations...-Cured Tobacco (u.s. Types 22, 23, and Foreign Type 96) § 29.2528 Leaf. Whole, unstemmed leaf. Leaf, when applied to tobacco in strip form, shall describe the divided unit of a whole leaf. [49 FR 16757, Apr. 20...

  17. 7 CFR 29.2528 - Leaf.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Leaf. 29.2528 Section 29.2528 Agriculture Regulations...-Cured Tobacco (u.s. Types 22, 23, and Foreign Type 96) § 29.2528 Leaf. Whole, unstemmed leaf. Leaf, when applied to tobacco in strip form, shall describe the divided unit of a whole leaf. [49 FR 16757, Apr. 20...

  18. 7 CFR 29.2528 - Leaf.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 7 Agriculture 2 2011-01-01 2011-01-01 false Leaf. 29.2528 Section 29.2528 Agriculture Regulations...-Cured Tobacco (u.s. Types 22, 23, and Foreign Type 96) § 29.2528 Leaf. Whole, unstemmed leaf. Leaf, when applied to tobacco in strip form, shall describe the divided unit of a whole leaf. [49 FR 16757, Apr. 20...

  19. A novel fluence map optimization model incorporating leaf sequencing constraints.

    PubMed

    Jin, Renchao; Min, Zhifang; Song, Enmin; Liu, Hong; Ye, Yinyu

    2010-02-21

    A novel fluence map optimization model incorporating leaf sequencing constraints is proposed to overcome the drawbacks of the current objective inside smoothing models. Instead of adding a smoothing item to the objective function, we add the total number of monitor unit (TNMU) requirement directly to the constraints which serves as an important factor to balance the fluence map optimization and leaf sequencing optimization process at the same time. Consequently, we formulate the fluence map optimization models for the trailing (left) leaf synchronized, leading (right) leaf synchronized and the interleaf motion constrained non-synchronized leaf sweeping schemes, respectively. In those schemes, the leaves are all swept unidirectionally from left to right. Each of those models is turned into a linear constrained quadratic programming model which can be solved effectively by the interior point method. Those new models are evaluated with two publicly available clinical treatment datasets including a head-neck case and a prostate case. As shown by the empirical results, our models perform much better in comparison with two recently emerged smoothing models (the total variance smoothing model and the quadratic smoothing model). For all three leaf sweeping schemes, our objective dose deviation functions increase much slower than those in the above two smoothing models with respect to the decreasing of the TNMU. While keeping plans in the similar conformity level, our new models gain much better performance on reducing TNMU.

  20. Costs of measuring leaf area index of corn

    NASA Technical Reports Server (NTRS)

    Daughtry, C. S. T.; Hollinger, S. E.

    1984-01-01

    The magnitude of plant-to-plant variability of leaf area of corn plants selected from uniform plots was examined and four representative methods for measuring leaf area index (LAI) were evaluated. The number of plants required and the relative costs for each sampling method were calculated to detect 10, 20, and 50% differences in LAI using 0.05 and 0.01 tests of significance and a 90% probability of success (beta = 0.1). The natural variability of leaf area per corn plant was nearly 10%. Additional variability or experimental error may be introduced by the measurement technique employed and by nonuniformity within the plot. Direct measurement of leaf area with an electronic area meter had the lowest CV, required that the fewest plants be sampled, but required approximately the same amount of time as the leaf area/weight ratio method to detect comparable differences. Indirect methods based on measurements of length and width of leaves required more plants but less total time than the direct method. Unless the coefficients for converting length and width to area are verified frequently, the indirect methods may be biased. When true differences in LAI among treatments exceed 50% of mean, all four methods are equal. The method of choice depends on the resources available, the differences to be detected, and what additional information, such as leaf weight or stalk weight, is also desired.

  1. Evolution of leaf form in marsileaceous ferns: evidence for heterochrony.

    PubMed

    Pryer, Kathleen M; Hearn, David J

    2009-02-01

    Using an explicit phylogenetic framework, ontogenetic patterns of leaf form are compared among the three genera of marsileaceous ferns (Marsilea, Regnellidium, and Pilularia) with the outgroup Asplenium to address the hypothesis that heterochrony played a role in their evolution. We performed a Fourier analysis on a developmental sequence of leaves from individuals of these genera. Principal components analysis of the harmonic coefficients was used to characterize the ontogenetic trajectories of leaf form in a smaller dimensional space. Results of this study suggest that the "evolutionary juvenilization" observed in these leaf sequences is best described using a mixed model of heterochrony (accelerated growth rate and early termination at a simplified leaf form). The later stages of the ancestral, more complex, ontogenetic pattern were lost in Marsileaceae, giving rise to the simplified adult leaves of Marsilea, Regnellidium, and Pilularia. Life-history traits such as ephemeral and uncertain habitats, high reproductive rates, and accelerated maturation, which are typical for marsileaceous ferns, suggest that they may be "r strategists." The evidence for heterochrony presented here illustrates that it has resulted in profound ecological and morphological consequences for the entire life history of Marsileaceae.

  2. From leaf longevity to canopy seasonality: a carbon optimality phenology model for tropical evergreen forests

    NASA Astrophysics Data System (ADS)

    Xu, X.; Medvigy, D.; Wu, J.; Wright, S. J.; Kitajima, K.; Pacala, S. W.

    2016-12-01

    Tropical evergreen forests play a key role in the global carbon, water and energy cycles. Despite apparent evergreenness, this biome shows strong seasonality in leaf litter and photosynthesis. Recent studies have suggested that this seasonality is not directly related to environmental variability but is dominated by seasonal changes of leaf development and senescence. Meanwhile, current terrestrial biosphere models (TBMs) can not capture this pattern because leaf life cycle is highly underrepresented. One challenge to model this leaf life cycle is the remarkable diversity in leaf longevity, ranging from several weeks to multiple years. Ecologists have proposed models where leaf longevity is regarded as a strategy to optimize carbon gain. However previous optimality models can not be readily integrated into TBMs because (i) there are still large biases in predicted leaf longevity and (ii) it is never tested whether the carbon optimality model can capture the observed seasonality in leaf demography and canopy photosynthesis. In this study, we develop a new carbon optimality model for leaf demography. The novelty of our approach is two-fold. First, we incorporate a mechanistic photosynthesis model that can better estimate leaf carbon gain. Second, we consider the interspecific variations in leaf senescence rate, which strongly influence the modelled optimal carbon gain. We test our model with a leaf trait database for Panamanian evergreen forests. Then, we apply the model at seasonal scale and compare simulated seasonality of leaf litter and canopy photosynthesis with in-situ observations from several Amazonian forest sites. We find that (i) compared with original optimality model, the regression slope between observed and predicted leaf longevity increases from 0.15 to 1.04 in our new model and (ii) that our new model can capture the observed seasonal variations of leaf demography and canopy photosynthesis. Our results suggest that the phenology in tropical evergreen

  3. A quest for the artificial leaf.

    PubMed

    Janna Olmos, Julian David; Kargul, Joanna

    2015-09-01

    It has been estimated that the energy captured in one hour of sunlight that reaches our planet is equivalent to annual energy production by human population globally. To efficiently capture the practically inexhaustible solar energy and convert it into high energy density solar fuels provides an attractive 'green' alternative to running our present day economies on rapidly depleting fossil fuels, especially in the context of ever growing global energy demand. Natural photosynthesis represents one of the most fundamental processes that sustain life on Earth. It provides nearly all the oxygen we breathe, the food we consume and fossil fuels that we so much depend on. Imitating the reactions that occur at the early stages of photosynthesis represents the main challenge in the quest for construction of an efficient, robust, self-renewing and cost-effective 'artificial leaf'. In this review we summarize the main molecular features of the natural solar energy converters, photosystem I and photosystem II, that allow them to operate at high quantum efficiencies, and thus inspire the smart matrix design of the artificial solar-to-fuel devices. We also discuss the main challenges that face the field and overview selected recent technological advances that have tremendously accelerated the race for a fully operational artificial leaf that could serve as a viable alternative to fossil fuels for energy production. Copyright © 2015 Elsevier Ltd. All rights reserved.

  4. Functional relationships of leafing intensity to plant height, growth form and leaf habit

    NASA Astrophysics Data System (ADS)

    Yan, En-Rong; Milla, Rubén; Aarssen, Lonnie W.; Wang, Xi-Hua

    2012-05-01

    Leafing intensity, i.e. the number of leaves per unit of stem volume or mass, is a common developmental correlate of leaf size. However, the ecological significance and the functional implications of variation in leafing intensity, other than its relation to leaf size, are unknown. Here, we explore its relationships with plant height, growth form, leaf size, and leaf habit to test a series of corollaries derived from the leafing intensity premium hypothesis. Volume-based leafing intensities and plant heights were recorded for 109 woody species from the subtropical evergreen broadleaf forests of eastern China. In addition, we compiled leafing intensity data from published literature, and combined it with our data to form a 398 species dataset, to test for differences of leafing intensity between plant growth forms (i.e. herbaceous and woody) and leaf habits (i.e. deciduous and evergreens). Leafing intensity was negatively correlated with plant height and individual leaf mass. Volume-based leafing intensities were significantly higher in herbaceous species than in woody species, and also higher in deciduous than in evergreen woody species. In conclusion, leafing intensity relates strongly to plant height, growth form, leaf size, and leaf habit in directions generally in accordance to the leafing intensity premium hypothesis. These results can be interpreted in terms of the evolution of adaptive strategies involving response to herbivory, competitive ability for light and reproductive economy.

  5. Rigidity and Plasticity of Leaf Carbon and Nitrogen Systematics in California Oaks

    NASA Astrophysics Data System (ADS)

    Krebs, T.; Baldocchi, D.; Xu, L.

    2003-12-01

    Mapping photosynthesis from space requires an understanding of photosynthetic efficiency. Current data sets prescribe global maps of photosynthetic parameters and relate them to greenness. It is the seasonality of greenness, and not of photosynthetic efficiency itself, which is presumed to drive photosynthesis. In fact, both greenness and photosynthetic efficiency convolve to produce seasonality in photosynthesis. If the scientific community is to globally retrieve photosynthetic rates from space, it must take this seasonality into account. We examine the rigidity and plasticity of photosynthetic capacity, its correlation to leaf nitrogen, and other leaf properties across geographic gradients of precipitation, soil moisture, air temperature, relative humidity and other measurables. In particular, these measurements focus on different species of oaks: blue oak (Quercus douglasii), coast live oak (Quercus agrifolia), black oak (Quercus velutina), and valley oak (Quercus lobata). Leaf chamber measurements with infrared gas analyzers and measurements of leaf specific mass, carbon isotope composition, and nitrogen content were performed in three Mediterranean ecosystems in California: Russell Reservation (coastal hills; oak woodland), Quail Ridge Reservation (near Lake Berryessa; Northern Coast Ranges; oak woodland), and Ione (Central Valley; oak savanna). Oaks of the same species adapted to more temperate microclimates such as shaded, north-facing slopes showed less pronounced seasonality in leaf nitrogen content and photosynthetic capacity. The comparison of evergreen and deciduous oak species yields relationships among leaf life span, specific leaf mass, and photosynthetic capacity that are consistent with the results of Reich. Our results confirm that oaks exhibit plasticity in their adaptation to more and less extreme environments. These results also explain why the deciduous oaks are less successful than the evergreen oaks near the coast and more successful in the

  6. BOREAS TE-12 Leaf Gas Exchange Data

    NASA Technical Reports Server (NTRS)

    Hall, Forrest G. (Editor); Curd, Shelaine (Editor); Arkebauer, Timothy J.; Yang, Litao

    2000-01-01

    The BOREAS TE-12 team collected several data sets in support of its efforts to characterize and interpret information on the reflectance, transmittance, and gas exchange of boreal vegetation. This data set contains measurements of leaf gas exchange conducted in the SSA during the growing seasons of 1994 and 1995 using a portable gas exchange system. The data are stored in tabular ASCII files. The data files are available on a CD-ROM (see document number 20010000884), or from the Oak Ridge National Laboratory (ORNL) Distributed Active Center (DAAC).

  7. Leaf manganese accumulation and phosphorus-acquisition efficiency.

    PubMed

    Lambers, Hans; Hayes, Patrick E; Laliberté, Etienne; Oliveira, Rafael S; Turner, Benjamin L

    2015-02-01

    Plants that deploy a phosphorus (P)-mobilising strategy based on the release of carboxylates tend to have high leaf manganese concentrations ([Mn]). This occurs because the carboxylates mobilise not only soil inorganic and organic P, but also a range of micronutrients, including Mn. Concentrations of most other micronutrients increase to a small extent, but Mn accumulates to significant levels, even when plants grow in soil with low concentrations of exchangeable Mn availability. Here, we propose that leaf [Mn] can be used to select for genotypes that are more efficient at acquiring P when soil P availability is low. Likewise, leaf [Mn] can be used to screen for belowground functional traits related to nutrient-acquisition strategies among species in low-P habitats. Copyright © 2014 Elsevier Ltd. All rights reserved.

  8. Plant traits and environment: floating leaf blade production and turnover of waterlilies

    PubMed Central

    2017-01-01

    Floating leaf blades of waterlilies fulfill several functions in wetland ecosystems by production, decomposition and turnover as well as exchange processes. Production and turnover rates of floating leaf blades of three waterlily species, Nuphar lutea (L.) Sm., Nymphaea alba L. and Nymphaea candida Presl, were studied in three freshwater bodies, differing in trophic status, pH and alkalinity. Length and percentages of leaf loss of marked leaf blades were measured weekly during the growing season. Area and biomass were calculated based on leaf length and were used to calculate the turnover rate of floating leaf blades. Seasonal changes in floating leaf production showed that values decreased in the order: Nymphaea alba, Nuphar lutea, Nymphaea candida. The highest production was reached for Nuphar lutea and Nymphaea alba in alkaline, eutrophic water bodies. The production per leaf was relatively high for both species in the acid water body. Nymphaea candida showed a very short vegetation period and low turnover rates. The ratio Total potential leaf biomass/Maximum potential leaf biomass (P/Bmax) of the three species ranged from 1.35–2.25. The ratio Vegetation period (Period with floating leaves)/Mean leaf life span ranged from 2.94–4.63, the ratio Growth period (Period with appearance of new floating leaves)/Vegetation period from 0.53–0.73. The clear differences between Nymphaea candida versus Nuphar lutea and Nymphaea alba, may be due to adaptations of Nymphaea candida to an Euro-Siberic climate with short-lasting summer conditions. PMID:28462025

  9. Environmental modification of yield and food composition of cowpea and leaf lettuce

    NASA Technical Reports Server (NTRS)

    Mitchell, Cary A.; Nielsen, Suzanne S.; Bubenheim, David L.

    1990-01-01

    Cowpea (Vigna unguiculata (L.) Walp.) and leaf lettuce (Lactuca sativa L.) are candidate species to provide ligume protein and starch or serve as a salad base for a nutritionally balanced and psychologically satisfying vegetarian diet in the Controlled Ecology Life Support System (CELSS). Various nutritional parameters are reported. Hydroponic leaf lettuce grew best under CO2 enrichment and photosynthetic photon flux (PPF) enhancement. Leaf protein content reached 36 percent with NH4(+) + NO3 nutrition; starch and free sugar content was as high as 7 or 8.4 percent of DW, respectively, for high PPF/CO2 enriched environments.

  10. Leaf longevity of Oxalis acetosella (Oxalidaceae) in the Catskill Mountains, New York, USA.

    PubMed

    Tessier, Jack T

    2004-09-01

    Leaf habit correlates with multiple physiological traits. Understanding ecophysiology is therefore dependent on knowledge of leaf habit. A variety of leaf habits exists within forest understory plant communities. Oxalis acetosella is one such understory plant and has long been considered a wintergreen, meaning that it keeps a set of leaves for one full year, replacing them with a new set during spring. To assess the leaf habit of O. acetosella and place it into a classification scheme of leaf habits, leaves of four populations of O. acetosella were repeatedly censused for two years in a northern hardwood forest of the Catskill Mountains, New York, USA. New leaves developed and old leaves senesced throughout the year, yielding a continual replacement of leaves and a summer peak in leaf number. Leaves that developed in the fall and winter had longer maximum life spans than leaves that developed during the summer. The name "seasonalgreen" is suggested to describe the continual development, senescence, and presence of leaves and annual peak in leaf number within O. acetosella. The functional significance of this leaf habit in this species and the possibility of its presence in other species deserve further study.

  11. Isolation and Structure Elucidation of the Terpene "[beta]"-Thujone from Cedar Leaf Oil

    ERIC Educational Resources Information Center

    French, Larry G.

    2011-01-01

    Western red cedar leaf affords an essential oil characterized by high thujone content. Students in an advanced organic chemistry lab course isolate a single thujone diastereoisomer from commercially available cedar leaf oil. Treatment of crude oil, containing roughly 70% thujone, predominately as [alpha]-thujone (6.5:1), with ethanolic sodium…

  12. Isolation and Structure Elucidation of the Terpene "[beta]"-Thujone from Cedar Leaf Oil

    ERIC Educational Resources Information Center

    French, Larry G.

    2011-01-01

    Western red cedar leaf affords an essential oil characterized by high thujone content. Students in an advanced organic chemistry lab course isolate a single thujone diastereoisomer from commercially available cedar leaf oil. Treatment of crude oil, containing roughly 70% thujone, predominately as [alpha]-thujone (6.5:1), with ethanolic sodium…

  13. Effects of nutrient addition on leaf chemistry, morphology, and photosynthetic capacity of three bog shrubs

    Treesearch

    Jill L. Bubier; Rose Smith; Sari Juutinen; Tim R. Moore; Rakesh Minocha; Stephanie Long; Subash. Minocha

    2011-01-01

    Plants in nutrient-poor environments typically have low foliar nitrogen (N) concentrations, long-lived tissues with leaf traits designed to use nutrients efficiently, and low rates of photosynthesis. We postulated that increasing N availability due to atmospheric deposition would increase photosynthetic capacity, foliar N, and specific leaf area (SLA) of bog shrubs. We...

  14. Temperature effect on leaf water deuterium enrichment and isotopic fractionation during leaf lipid biosynthesis: results from controlled growth of C3 and C4 land plants.

    PubMed

    Zhou, Youping; Grice, Kliti; Chikaraishi, Yoshito; Stuart-Williams, Hilary; Farquhar, Graham D; Ohkouchi, Naohiko

    2011-02-01

    The hydrogen isotopic ratios ((2)H/(1)H) of land plant leaf water and the carbon-bound hydrogen of leaf wax lipids are valuable indicators for climatic, physiological, metabolic and geochemical studies. Temperature will exert a profound effect on the stable isotopic composition of leaf water and leaf lipids as it directly influences the isotopic equilibrium (IE) during leaf water evaporation and cellular water dissociation. It is also expected to affect the kinetics of enzymes involved in lipid biosynthesis, and therefore the balance of hydrogen inputs along different biochemical routes. We conducted a controlled growth experiment to examine the effect of temperature on the stable hydrogen isotopic composition of leaf water and the biological and biochemical isotopic fractionations during lipid biosynthesis. We find that leaf water (2)H enrichment at 20°C is lower than that at 30°C. This is contrary to the expectation that at lower temperatures leaf water should be more enriched in (2)H due to a larger equilibrium isotope effect associated with evapotranspiration from the leaf if all other variables are held constant. A hypothesis is presented to explain the apparent discrepancy whereby lower temperature-induced down-regulation of available aquaporin water channels and/or partial closure of transmembrane water channel forces water flow to "detour" to a more convoluted apoplastic pathway, effectively increasing the length over which diffusion acts against advection as described by the Péclet effect (Farquhar and Lloyd, 1993) and decreasing the average leaf water enrichment. The impact of temperature on leaf water enrichment is not reflected in the biological isotopic fractionation or the biochemical isotopic fractionation during lipid biosynthesis. Neither the biological nor biochemical fractionations at 20°C are significantly different from that at 30°C, implying that temperature has a negligible effect on the isotopic fractionation during lipid biosynthesis

  15. Is the spherical leaf inclination angle distribution a valid assumption for temperate and boreal tree and shrub species?

    NASA Astrophysics Data System (ADS)

    Pisek, J.

    2012-12-01

    Directional distribution of leaves is one primary parameter for determining the radiation transmission through the canopy. When inverting canopy transmittance measurements for estimating the leaf area index or foliage clumping, incorrect assumptions on leaf angles may lead to considerable errors. Often spherical distribution of leaf normals is assumed, i.e. leaf normals are assumed to have no preferred direction in situations where no measurement data are available. The goal of this study is to examine if a spherical leaf angle distribution and the resulting isotropic G-function (G≡0.5) is indeed a valid assumption for temperate and boreal tree and shrub species. Leaf angle distributions were measured for over 80 deciduous broadleaf species commonly found in temperate and boreal ecoclimatic regions. The leaf inclination angles were obtained by sampling the complete vertical extent of trees and shrubs using a recently introduced technique based on digital photography. It is found a spherical leaf angle distribution is not a valid assumption for both tree and shrub species in temperate and boreal ecoclimatic regions. Given the influence of leaf angle distribution on inverting clumping and LAI estimates from canopy transmittance measurements, it is recommended to use planophile or plagiophile leaf angle distribution as more appropriate for modeling radiation transmission in temperate and boreal ecoclimatic regions when no actual leaf inclination angle measurements are available.

  16. Seasonal availability of resources and habitat degradation for the western tree-hole mosquito, Aedes sierrensis.

    PubMed

    Maciá, A; Bradshaw, W E

    2000-10-01

    The nutrient base of aquatic tree-hole communities is derived from leaf litter, benthic detritus, and water flowing down the tree trunk (stemflow water). Previous studies in eastern North America with the mosquito, Aedes triseriatus, have identified leaf litter as a major and stemflow water as a minor source of mosquito nutrition, but did not consider the role of the benthic detritus or how the aggregate or relative contribution of these sources of mosquito nutrition changed during the year. We use the leaf litter, benthic detritus, and stemflow water from tree holes in western Oregon (USA) to determine how these substrates affect mass at metamorphosis, biomass yield, and fitness (cohort replacement rate; R 0) of the mosquito, Aedes sierrensis, through both natural and simulated winters, the normal growing season for larvae in tree holes. We found that fresh leaf litter constitutes the major determinant of mosquito fitness by a factor of >15:1 over any other substrate taken directly from tree holes in nature. The other substrates, including the benthic detritus, individually make only a meager contribution to mosquito fitness but, when added to the leaf litter, can sustain yield and improve fitness at high, limiting larval densities. Nutritional quality of tree-hole substrates declines by >90% from early (fall) to late (spring) in the larval growing season. At both times of year, the coarse or fine detritus provide minor resources, and stemflow water provides no detectable contribution to mosquito nutrition. The resources in the litter are not transported during the year to the benthic detritus; rather, these resources are either exploited by mosquitoes when they first become available, or they deteriorate and become progressively more unavailable to them. Growth and development of A. sierrensis feeding on dried and reconstituted tree-hole contents during a 6-month simulated winter in the laboratory showed: (1) the same relative contributions of leaf litter

  17. Interpreting chlorophyll fluorescence signals: the effects of leaf age

    NASA Astrophysics Data System (ADS)

    Albert, L.; Vergeli, P.; Martins, G.; Saleska, S. R.; Huxman, T. E.

    2015-12-01

    Remote sensing of sun-induced chlorophyll fluorescence (SIF) promises robust estimation of carbon uptake across landscapes, as studies of plant physiology have shown that fluorescence emission is directly linked to photosynthesis at the leaf level. Yet most leaf-level studies demonstrating the link between chlorophyll fluorescence and photosynthesis have studied leaves in their prime: leaves that recently finished expansion and have yet to senesce. By contrast, remote sensing of landscapes involves observing leaves of different ages. For example, broadleaf deciduous forests and annual plant communities in temperate regions have leaves that develop and then senesce over the course of a growing season. In this experiment, we explored how leaf age and moisture availability affect steady-state fluoresence (Fs) at the leaf level. We simultaneously measured net photosynthesis (Anet) and Fs for leaves of known ages on greenhouse-grown dwarf Helianthus Annuus (sunflowers) from two watering treatments. To monitor plant water status, we measured pre-dawn water potential, and, for a subset of leaves, osmotic potential. Fully expanded or near-fully expanded leaves (~8 to ~23 days old) had higher Anet at saturating light than young, expanding leaves (less than 8 days old) or old leaves nearing senescence (>23 days old). We found a positive relationship between Fs and Anet, suggesting that the link between fluorescence emission and photosynthesis is robust across leaves of different ages. However, leaf age had marked effects on the light response curve of photosynthesis and fluorescence metrics. These results suggest that leaf age distribution, and changes in leaf age distribution due to phenology, should be considered when interpreting SIF at the landscape level.

  18. Rapid Leaf Deployment Strategies in a Deciduous Savanna

    PubMed Central

    2016-01-01

    Deciduous plants avoid the costs of maintaining leaves in the unfavourable season, but carry the costs of constructing new leaves every year. Deciduousness is therefore expected in ecological situations with pronounced seasonality and low costs of leaf construction. In our study system, a seasonally dry tropical savanna, many trees are deciduous, suggesting that leaf construction costs must be low. Previous studies have, however, shown that nitrogen is limiting in this system, suggesting that leaf construction costs are high. Here we examine this conundrum using a time series of soil moisture availability, leaf phenology and nitrogen distribution in the tree canopy to illustrate how trees resorb nitrogen before leaf abscission and use stored reserves of nitrogen and carbon to construct new leaves at the onset of the growing season. Our results show that trees deployed leaves shortly before and in anticipation of the first rains with its associated pulse of nitrogen mineralisation. Our results also show that trees rapidly constructed a full canopy of leaves within two weeks of the first rains. We detected an increase in leaf nitrogen content that corresponded with the first rains and with the movement of nitrogen to more distal branches, suggesting that stored nitrogen reserves are used to construct leaves. Furthermore the stable carbon isotope ratios (δ13C) of these leaves suggest the use of stored carbon for leaf construction. Our findings suggest that the early deployment of leaves using stored nitrogen and carbon reserves is a strategy that is integrally linked with the onset of the first rains. This strategy may confer a competitive advantage over species that deploy leaves at or after the onset of the rains. PMID:27310398

  19. Leaf water deuterium enrichment shapes leaf wax n-alkane δD values of angiosperm plants II: Observational evidence and global implications

    NASA Astrophysics Data System (ADS)

    Kahmen, Ansgar; Hoffmann, Bernd; Schefuß, Enno; Arndt, Stefan K.; Cernusak, Lucas A.; West, Jason B.; Sachse, Dirk

    2013-06-01

    Leaf wax n-alkanes are long-chain hydrocarbons that can persist in sedimentary records over geological timescales. Since their hydrogen isotopic composition (expressed as a δD value) can be correlated to the δD values of precipitation, leaf wax n-alkane δD values have been advocated as new and powerful proxies for paleohydrological research. The exact type of hydrological information that is recorded in the δD values of leaf wax n-alkanes remains, however, unclear. In a companion paper we provide experimental evidence showing that the δD values of leaf wax n-alkanes of angiosperm plants grown under controlled environmental conditions not only reflect δD values of precipitation - as has often been assumed - but that evaporative deuterium (D)-enrichment of leaf water has an additional critical effect on their δD values. Here we present a detailed observational study that illustrates that evaporative D-enrichment of leaf water also affects the δD values of leaf wax n-alkanes in plants from natural ecosystems along a 1500 km climate gradient in Northern Australia. Based on global simulations of leaf water D-enrichment we show that the effects of evaporative D-enrichment of leaf water on leaf wax n-alkane δD values is relevant in all biomes but that it is particularly important in arid environments. Given the combined influence of precipitation δD values and leaf water D-enrichment we argue that leaf wax n-alkane δD values contain an integrated signal that can provide general hydrological information, e.g. on the aridity of a catchment area. We also suggest that more specific hydrological information and even plant physiological information can be obtained from leaf wax n-alkanes if additional indicators are available to constrain the plant- and precipitation-derived influences on their δD values. As such, our findings have important implications for the interpretation of leaf wax n-alkane δD values from paleohydrological records. In addition, our

  20. Compounds with anti-influenza activity: present and future of strategies for the optimal treatment and management of influenza. Part I: Influenza life-cycle and currently available drugs.

    PubMed

    Gasparini, R; Amicizia, D; Lai, P L; Bragazzi, N L; Panatto, D

    2014-09-01

    Influenza is a contagious respiratory acute viral disease characterized by a short incubation period, high fever and respiratory and systemic symptoms. The burden of influenza is very heavy. Indeed, the World Health Organization (WHO) estimates that annual epidemics affect 5-15% of the world's population, causing up to 4-5 million severe cases and from 250,000 to 500,000 deaths. In order to design anti-influenza molecules and compounds, it is important to understand the complex replication cycle of the influenza virus. Replication is achieved through various stages. First, the virus must engage the sialic acid receptors present on the free surface of the cells of the respiratory tract. The virus can then enter the cells by different routes (clathrin-mediated endocytosis or CME, caveolae-dependent endocytosis or CDE, clathrin-caveolae-independent endocytosis, or macropinocytosis). CME is the most usual pathway; the virus is internalized into an endosomal compartment, from which it must emerge in order to release its nucleic acid into the cytosol. The ribonucleoprotein must then reach the nucleus in order to begin the process of translation of its genes and to transcribe and replicate its nucleic acid. Subsequently, the RNA segments, surrounded by the nucleoproteins, must migrate to the cell membrane in order to enable viral assembly. Finally, the virus must be freed to invade other cells of the respiratory tract. All this is achieved through a synchronized action of molecules that perform multiple enzymatic and catalytic reactions, currently known only in part, and for which many inhibitory or competitive molecules have been studied. Some of these studies have led to the development of drugs that have been approved, such as Amantadine, Rimantadine, Oseltamivir, Zanamivir, Peramivir, Laninamivir, Ribavirin and Arbidol. This review focuses on the influenza life-cycle and on the currently available drugs, while potential antiviral compounds for the prevention and

  1. Spectral reflectance relationships to leaf water stress

    NASA Technical Reports Server (NTRS)

    Ripple, William J.

    1986-01-01

    Spectral reflectance data were collected from detached snapbean leaves in the laboratory with a multiband radiometer. Four experiments were designed to study the spectral response resulting from changes in leaf cover, relative water content of leaves, and leaf water potential. Spectral regions included in the analysis were red (630-690 nm), NIR (760-900 nm), and mid-IR (2.08-2.35 microns). The red and mid-IR bands showed sensitivity to changes in both leaf cover and relative water content of leaves. The NIR was only highly sensitive to changes in leaf cover. Results provided evidence that mid-IR reflectance was governed primarily by leaf moisture content, although soil reflectance was an important factor when leaf cover was less than 100 percent. High correlations between leaf water potentials and reflectance were attributed to covariances with relative water content of leaves and leaf cover.

  2. Spectral reflectance relationships to leaf water stress

    NASA Technical Reports Server (NTRS)

    Ripple, William J.

    1986-01-01

    Spectral reflectance data were collected from detached snapbean leaves in the laboratory with a multiband radiometer. Four experiments were designed to study the spectral response resulting from changes in leaf cover, relative water content of leaves, and leaf water potential. Spectral regions included in the analysis were red (630-690 nm), NIR (760-900 nm), and mid-IR (2.08-2.35 microns). The red and mid-IR bands showed sensitivity to changes in both leaf cover and relative water content of leaves. The NIR was only highly sensitive to changes in leaf cover. Results provided evidence that mid-IR reflectance was governed primarily by leaf moisture content, although soil reflectance was an important factor when leaf cover was less than 100 percent. High correlations between leaf water potentials and reflectance were attributed to covariances with relative water content of leaves and leaf cover.

  3. Behavior of Leaf Meristems and Their Modification

    PubMed Central

    Ichihashi, Yasunori; Tsukaya, Hirokazu

    2015-01-01

    A major source of diversity in flowering plant form is the extensive variability of leaf shape and size. Leaf formation is initiated by recruitment of a handful of cells flanking the shoot apical meristem (SAM) to develop into a complex three-dimensional structure. Leaf organogenesis depends on activities of several distinct meristems that are established and spatiotemporally differentiated after the initiation of leaf primordia. Here, we review recent findings in the gene regulatory networks that orchestrate leaf meristem activities in a model plant Arabidopsis thaliana. We then discuss recent key studies investigating the natural variation in leaf morphology to understand how the gene regulatory networks modulate leaf meristems to yield a substantial diversity of leaf forms during the course of evolution. PMID:26648955

  4. Variations of leaf N and P concentrations in shrubland biomes across northern China: phylogeny, climate, and soil

    NASA Astrophysics Data System (ADS)

    Yang, Xian; Chi, Xiulian; Ji, Chengjun; Liu, Hongyan; Ma, Wenhong; Mohhammat, Anwar; Shi, Zhaoyong; Wang, Xiangping; Yu, Shunli; Yue, Ming; Tang, Zhiyao

    2016-08-01

    Concentrations of leaf nitrogen (N) and phosphorus (P) are two key traits of plants for ecosystem functioning and dynamics. Foliar stoichiometry varies remarkably among life forms. However, previous studies have focused on the stoichiometric patterns of trees and grasses, leaving a significant knowledge gap for shrubs. In this study, we explored the intraspecific and interspecific variations of leaf N and P concentrations in response to the changes in climate, soil property, and evolutionary history. We analysed 1486 samples composed of 163 shrub species from 361 shrubland sites in northern China encompassing 46.1° (86.7-132.8° E) in longitude and 19.8° (32.6-52.4° N) in latitude. Leaf N concentrations decreased with precipitation, while leaf P concentrations decreased with temperature and increased with precipitation and soil total P concentrations. Both leaf N and P concentrations were phylogenetically conserved, but leaf P concentrations were less conserved than leaf N concentrations. At the community level, climate explained more interspecific variation of leaf nutrient concentrations, while soil nutrients explained most of the intraspecific variation. These results suggested that leaf N and P concentrations responded to climate, soil, and phylogeny in different ways. Climate influenced the community chemical traits through the shift in species composition, whereas soil directly influenced the community chemical traits. New patterns were discovered using our observations on specific regions and vegetation types, which improved our knowledge of broad biogeographic patterns of leaf chemical traits.

  5. Comparative analyses of leaf anatomy of dicotyledonous species in Tibetan and Inner Mongolian grasslands.

    PubMed

    Ma, Jianjing; Ji, Chengjun; Han, Mei; Zhang, Tingfang; Yan, Xuedong; Hu, Dong; Zeng, Hui; He, Jinsheng

    2012-01-01

    Knowledge of the leaf anatomy of grassland plants is crucial for understanding how these plants adapt to the environment. Tibetan alpine grasslands and Inner Mongolian temperate grasslands are two major grassland types in northern China. Tibetan alpine grasslands occur in high-altitude regions where the low temperatures limit plant growth. Inner Mongolian temperate grasslands are found in arid regions where moisture is the limiting factor. Few comparative studies concerning the leaf anatomy of grassland plants of the Tibetan Plateau and Inner Mongolian Plateau have been conducted. We examined leaf characteristics at 71 sites and among 65 species, across the alpine grasslands of the Tibetan Plateau and the temperate grasslands of the Inner Mongolian Plateau. We compared the leaf structures of plants with different life forms and taxonomies, and their adaptation to arid or cold environments. We explored relationships among leaf features and the effects of climatic factors (i.e., growing season temperature and precipitation) on leaf characteristics. Our results showed that (i) there were significant differences in leaf anatomy between Tibetan alpine and Inner Mongolian temperate grasslands. Except for mesophyll cell density, the values obtained for thickness of leaf tissue, surface area and volume of mesophyll cells were larger on the Tibetan Plateau than on the Inner Mongolian Plateau. (ii) Within the same family or genus, leaf anatomy showed significant differences between two regions, and trends were consistent with those of whole species. (iii) Leaf anatomy of woody and herbaceous plants also showed significant differences between the regions. Except for mesophyll cell density, the values obtained for the thickness of leaf tissue, and the surface area and volume of mesophyll cells were larger in herbaceous than in woody plants. (iv) Leaf anatomical traits changed accordingly. Total leaf thickness, thicknesses of lower and upper epidermal cells, and surface area

  6. Control of Leaf Expansion: A Developmental Switch from Metabolics to Hydraulics1[W][OA

    PubMed Central

    Pantin, Florent; Simonneau, Thierry; Rolland, Gaëlle; Dauzat, Myriam; Muller, Bertrand

    2011-01-01

    Leaf expansion is the central process by which plants colonize space, allowing energy capture and carbon acquisition. Water and carbon emerge as main limiting factors of leaf expansion, but the literature remains controversial about their respective contributions. Here, we tested the hypothesis that the importance of hydraulics and metabolics is organized according to both dark/light fluctuations and leaf ontogeny. For this purpose, we established the developmental pattern of individual leaf expansion during days and nights in the model plant Arabidopsis (Arabidopsis thaliana). Under control conditions, decreases in leaf expansion were observed at night immediately after emergence, when starch reserves were lowest. These nocturnal decreases were strongly exaggerated in a set of starch mutants, consistent with an early carbon limitation. However, low-light treatment of wild-type plants had no influence on these early decreases, implying that expansion can be uncoupled from changes in carbon availability. From 4 d after leaf emergence onward, decreases of leaf expansion were observed in the daytime. Using mutants impaired in stomatal control of transpiration as well as plants grown under soil water deficit or high air humidity, we gathered evidence that these diurnal decreases were the signature of a hydraulic limitation that gradually set up as the leaf developed. Changes in leaf turgor were consistent with this pattern. It is concluded that during the course of leaf ontogeny, the predominant control of leaf expansion switches from metabolics to hydraulics. We suggest that the leaf is better armed to buffer variations in the former than in the latter. PMID:21474437

  7. LEAF: A Microcomputer Program for Constructing the Tukey Stem and Leaf Graph.

    ERIC Educational Resources Information Center

    Pascale, Pietro J.; Smith, Joseph

    1986-01-01

    This paper presents a BASIC microcomputer program that constructs the Tukey (1977) stem and leaf graph. Options within the LEAF program include a modified stem and leaf where the stem is split and a parallel stem and leaf graph where two separate sets of data are displayed from a common stem. (Author)

  8. Experimental manipulation of leaf litter colonization by aquatic invertebrates in a third order tropical stream.

    PubMed

    Uieda, V S; Carvalho, E M

    2015-05-01

    Through a manipulative experiment, the colonization of leaf litter by invertebrates was investigated in two sections of a tropical stream (spatial scale) that differed in function of the canopy cover, one with the presence (closed area) and another without riparian vegetation (open area), during one month of the dry and one of the wet season (temporal scale). The work aimed to verify differences related to four variables: season, canopy cover, leaf type and leaf condition. Litter bags containing arboreal and herbaceous leaves (leaf type variable), non-conditioned and preconditioned (leaf condition variable) were placed at the bottom of the stream in each area (canopy cover variable) and season (dry and wet), and removed after 13-day colonization. The analysis of the remaining litter dry mass per leaf bag emphasizes differences related mainly to seasonality, canopy cover and leaf type, although leaf condition was also important when combined with those three factors. Comparing the abundance of invertebrates per treatment, there was a tendency of high predominance of Chironomidae during the dry season and greater taxa diversity and evenness during the wet season, when the water flow increase could alter the availability of microhabitats for local fauna. Even though canopy cover alone was not a significant source of variation in the abundance of invertebrates, the results showed a tendency of a combined effect of canopy cover with seasonality and leaf condition.

  9. 7 CFR 29.3527 - Leaf structure.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... Type 95) § 29.3527 Leaf structure. The cell development of a leaf as indicated by its porosity. (See... 7 Agriculture 2 2010-01-01 2010-01-01 false Leaf structure. 29.3527 Section 29.3527 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing...

  10. 7 CFR 29.3035 - Leaf structure.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... Leaf structure. The cell development of a leaf as indicated by its porosity or solidity. (See Elements... 7 Agriculture 2 2010-01-01 2010-01-01 false Leaf structure. 29.3035 Section 29.3035 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing...

  11. 7 CFR 29.1030 - Leaf structure.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... Type 92) § 29.1030 Leaf structure. The cell development of a leaf as indicated by its porosity. (See... 7 Agriculture 2 2012-01-01 2012-01-01 false Leaf structure. 29.1030 Section 29.1030 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing...

  12. 7 CFR 29.3035 - Leaf structure.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... Leaf structure. The cell development of a leaf as indicated by its porosity or solidity. (See Elements... 7 Agriculture 2 2011-01-01 2011-01-01 false Leaf structure. 29.3035 Section 29.3035 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing...

  13. 7 CFR 29.3035 - Leaf structure.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... Leaf structure. The cell development of a leaf as indicated by its porosity or solidity. (See Elements... 7 Agriculture 2 2013-01-01 2013-01-01 false Leaf structure. 29.3035 Section 29.3035 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing...

  14. 7 CFR 29.3035 - Leaf structure.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... Leaf structure. The cell development of a leaf as indicated by its porosity or solidity. (See Elements... 7 Agriculture 2 2014-01-01 2014-01-01 false Leaf structure. 29.3035 Section 29.3035 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing...

  15. 7 CFR 29.3527 - Leaf structure.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... Type 95) § 29.3527 Leaf structure. The cell development of a leaf as indicated by its porosity. (See... 7 Agriculture 2 2014-01-01 2014-01-01 false Leaf structure. 29.3527 Section 29.3527 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing...

  16. 7 CFR 29.1030 - Leaf structure.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... Type 92) § 29.1030 Leaf structure. The cell development of a leaf as indicated by its porosity. (See... 7 Agriculture 2 2014-01-01 2014-01-01 false Leaf structure. 29.1030 Section 29.1030 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing...

  17. 7 CFR 29.3527 - Leaf structure.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... Type 95) § 29.3527 Leaf structure. The cell development of a leaf as indicated by its porosity. (See... 7 Agriculture 2 2013-01-01 2013-01-01 false Leaf structure. 29.3527 Section 29.3527 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing...

  18. 7 CFR 29.6023 - Leaf structure.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... INSPECTION Standards Definitions § 29.6023 Leaf structure. The cell development of a leaf as indicated by its... 7 Agriculture 2 2013-01-01 2013-01-01 false Leaf structure. 29.6023 Section 29.6023 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing...

  19. 7 CFR 29.3035 - Leaf structure.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... Leaf structure. The cell development of a leaf as indicated by its porosity or solidity. (See Elements... 7 Agriculture 2 2012-01-01 2012-01-01 false Leaf structure. 29.3035 Section 29.3035 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing...

  20. 7 CFR 29.6023 - Leaf structure.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... INSPECTION Standards Definitions § 29.6023 Leaf structure. The cell development of a leaf as indicated by its... 7 Agriculture 2 2014-01-01 2014-01-01 false Leaf structure. 29.6023 Section 29.6023 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing...

  1. 7 CFR 29.1030 - Leaf structure.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... Type 92) § 29.1030 Leaf structure. The cell development of a leaf as indicated by its porosity. (See... 7 Agriculture 2 2010-01-01 2010-01-01 false Leaf structure. 29.1030 Section 29.1030 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing...

  2. 7 CFR 29.6023 - Leaf structure.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... INSPECTION Standards Definitions § 29.6023 Leaf structure. The cell development of a leaf as indicated by its... 7 Agriculture 2 2010-01-01 2010-01-01 false Leaf structure. 29.6023 Section 29.6023 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing...

  3. 7 CFR 29.3527 - Leaf structure.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... Type 95) § 29.3527 Leaf structure. The cell development of a leaf as indicated by its porosity. (See... 7 Agriculture 2 2011-01-01 2011-01-01 false Leaf structure. 29.3527 Section 29.3527 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing...

  4. 7 CFR 29.1030 - Leaf structure.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... Type 92) § 29.1030 Leaf structure. The cell development of a leaf as indicated by its porosity. (See... 7 Agriculture 2 2011-01-01 2011-01-01 false Leaf structure. 29.1030 Section 29.1030 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing...

  5. 7 CFR 29.3527 - Leaf structure.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... Type 95) § 29.3527 Leaf structure. The cell development of a leaf as indicated by its porosity. (See... 7 Agriculture 2 2012-01-01 2012-01-01 false Leaf structure. 29.3527 Section 29.3527 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing...

  6. 7 CFR 29.6023 - Leaf structure.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... INSPECTION Standards Definitions § 29.6023 Leaf structure. The cell development of a leaf as indicated by its... 7 Agriculture 2 2011-01-01 2011-01-01 false Leaf structure. 29.6023 Section 29.6023 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing...

  7. 7 CFR 29.1030 - Leaf structure.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... Type 92) § 29.1030 Leaf structure. The cell development of a leaf as indicated by its porosity. (See... 7 Agriculture 2 2013-01-01 2013-01-01 false Leaf structure. 29.1030 Section 29.1030 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing...

  8. 7 CFR 29.6023 - Leaf structure.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... INSPECTION Standards Definitions § 29.6023 Leaf structure. The cell development of a leaf as indicated by its... 7 Agriculture 2 2012-01-01 2012-01-01 false Leaf structure. 29.6023 Section 29.6023 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing...

  9. 7 CFR 29.3528 - Leaf surface.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Leaf surface. 29.3528 Section 29.3528 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing... Type 95) § 29.3528 Leaf surface. The roughness or smoothness of the web or lamina of a tobacco leaf...

  10. 7 CFR 29.3528 - Leaf surface.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 7 Agriculture 2 2014-01-01 2014-01-01 false Leaf surface. 29.3528 Section 29.3528 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing... Type 95) § 29.3528 Leaf surface. The roughness or smoothness of the web or lamina of a tobacco leaf...

  11. 7 CFR 29.2529 - Leaf scrap.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 7 Agriculture 2 2012-01-01 2012-01-01 false Leaf scrap. 29.2529 Section 29.2529 Agriculture...-Cured Tobacco (u.s. Types 22, 23, and Foreign Type 96) § 29.2529 Leaf scrap. A byproduct of unstemmed tobacco. Leaf scrap results from handling unstemmed tobacco and consists of loose and tangled whole or...

  12. 7 CFR 29.6022 - Leaf scrap.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 7 Agriculture 2 2014-01-01 2014-01-01 false Leaf scrap. 29.6022 Section 29.6022 Agriculture... INSPECTION Standards Definitions § 29.6022 Leaf scrap. A byproduct of unstemmed tobacco Leaf scrap results from handling unstemmed tobacco and consists of loose and tangled whole or broken leaves. ...

  13. 7 CFR 29.2529 - Leaf scrap.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 7 Agriculture 2 2013-01-01 2013-01-01 false Leaf scrap. 29.2529 Section 29.2529 Agriculture...-Cured Tobacco (u.s. Types 22, 23, and Foreign Type 96) § 29.2529 Leaf scrap. A byproduct of unstemmed tobacco. Leaf scrap results from handling unstemmed tobacco and consists of loose and tangled whole or...

  14. 7 CFR 29.3034 - Leaf scrap.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 7 Agriculture 2 2013-01-01 2013-01-01 false Leaf scrap. 29.3034 Section 29.3034 Agriculture... Leaf scrap. A by-product of unstemmed tobacco. Leaf scrap results from handling unstemmed tobacco and consists of loose and tangled whole or broken leaves. ...

  15. 7 CFR 29.3526 - Leaf scrap.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 7 Agriculture 2 2012-01-01 2012-01-01 false Leaf scrap. 29.3526 Section 29.3526 Agriculture... Type 95) § 29.3526 Leaf scrap. A byproduct of unstemmed tobacco Leaf scrap results from handling unstemmed tobacco and consists of loose and tangled whole or broken leaves. [30 FR 9207, July 23, 1965...

  16. 7 CFR 29.6022 - Leaf scrap.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 7 Agriculture 2 2013-01-01 2013-01-01 false Leaf scrap. 29.6022 Section 29.6022 Agriculture... INSPECTION Standards Definitions § 29.6022 Leaf scrap. A byproduct of unstemmed tobacco Leaf scrap results from handling unstemmed tobacco and consists of loose and tangled whole or broken leaves. ...

  17. 7 CFR 29.3034 - Leaf scrap.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 7 Agriculture 2 2012-01-01 2012-01-01 false Leaf scrap. 29.3034 Section 29.3034 Agriculture... Leaf scrap. A by-product of unstemmed tobacco. Leaf scrap results from handling unstemmed tobacco and consists of loose and tangled whole or broken leaves. [24 FR 8771, Oct. 29, 1959. Redesignated at 49 FR...

  18. 7 CFR 29.2277 - Leaf scrap.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 7 Agriculture 2 2012-01-01 2012-01-01 false Leaf scrap. 29.2277 Section 29.2277 Agriculture... INSPECTION Standards Official Standard Grades for Virginia Fire-Cured Tobacco (u.s. Type 21) § 29.2277 Leaf scrap. A byproduct of unstemmed tobacco. Leaf scrap results from handling unstemmed tobacco and consists...

  19. 7 CFR 29.2529 - Leaf scrap.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 7 Agriculture 2 2014-01-01 2014-01-01 false Leaf scrap. 29.2529 Section 29.2529 Agriculture...-Cured Tobacco (u.s. Types 22, 23, and Foreign Type 96) § 29.2529 Leaf scrap. A byproduct of unstemmed tobacco. Leaf scrap results from handling unstemmed tobacco and consists of loose and tangled whole or...

  20. 7 CFR 29.2277 - Leaf scrap.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 7 Agriculture 2 2013-01-01 2013-01-01 false Leaf scrap. 29.2277 Section 29.2277 Agriculture... INSPECTION Standards Official Standard Grades for Virginia Fire-Cured Tobacco (u.s. Type 21) § 29.2277 Leaf scrap. A byproduct of unstemmed tobacco. Leaf scrap results from handling unstemmed tobacco and consists...

  1. 7 CFR 29.2277 - Leaf scrap.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 7 Agriculture 2 2014-01-01 2014-01-01 false Leaf scrap. 29.2277 Section 29.2277 Agriculture... INSPECTION Standards Official Standard Grades for Virginia Fire-Cured Tobacco (u.s. Type 21) § 29.2277 Leaf scrap. A byproduct of unstemmed tobacco. Leaf scrap results from handling unstemmed tobacco and consists...

  2. 7 CFR 29.3526 - Leaf scrap.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 7 Agriculture 2 2014-01-01 2014-01-01 false Leaf scrap. 29.3526 Section 29.3526 Agriculture... Type 95) § 29.3526 Leaf scrap. A byproduct of unstemmed tobacco Leaf scrap results from handling unstemmed tobacco and consists of loose and tangled whole or broken leaves. ...

  3. 7 CFR 29.3034 - Leaf scrap.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 7 Agriculture 2 2014-01-01 2014-01-01 false Leaf scrap. 29.3034 Section 29.3034 Agriculture... Leaf scrap. A by-product of unstemmed tobacco. Leaf scrap results from handling unstemmed tobacco and consists of loose and tangled whole or broken leaves. ...

  4. 7 CFR 29.6022 - Leaf scrap.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 7 Agriculture 2 2012-01-01 2012-01-01 false Leaf scrap. 29.6022 Section 29.6022 Agriculture... INSPECTION Standards Definitions § 29.6022 Leaf scrap. A byproduct of unstemmed tobacco Leaf scrap results from handling unstemmed tobacco and consists of loose and tangled whole or broken leaves. ...

  5. 7 CFR 29.3526 - Leaf scrap.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 7 Agriculture 2 2013-01-01 2013-01-01 false Leaf scrap. 29.3526 Section 29.3526 Agriculture... Type 95) § 29.3526 Leaf scrap. A byproduct of unstemmed tobacco Leaf scrap results from handling unstemmed tobacco and consists of loose and tangled whole or broken leaves. ...

  6. 7 CFR 29.3034 - Leaf scrap.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 7 Agriculture 2 2011-01-01 2011-01-01 false Leaf scrap. 29.3034 Section 29.3034 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing... Leaf scrap. A by-product of unstemmed tobacco. Leaf scrap results from handling unstemmed tobacco and...

  7. 7 CFR 29.3526 - Leaf scrap.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 7 Agriculture 2 2011-01-01 2011-01-01 false Leaf scrap. 29.3526 Section 29.3526 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing... Type 95) § 29.3526 Leaf scrap. A byproduct of unstemmed tobacco Leaf scrap results from handling...

  8. 7 CFR 29.6022 - Leaf scrap.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Leaf scrap. 29.6022 Section 29.6022 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing... INSPECTION Standards Definitions § 29.6022 Leaf scrap. A byproduct of unstemmed tobacco Leaf scrap results...

  9. 7 CFR 29.2529 - Leaf scrap.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Leaf scrap. 29.2529 Section 29.2529 Agriculture...-Cured Tobacco (u.s. Types 22, 23, and Foreign Type 96) § 29.2529 Leaf scrap. A byproduct of unstemmed tobacco. Leaf scrap results from handling unstemmed tobacco and consists of loose and tangled whole or...

  10. 7 CFR 29.3034 - Leaf scrap.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Leaf scrap. 29.3034 Section 29.3034 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing... Leaf scrap. A by-product of unstemmed tobacco. Leaf scrap results from handling unstemmed tobacco and...

  11. 7 CFR 29.2529 - Leaf scrap.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 7 Agriculture 2 2011-01-01 2011-01-01 false Leaf scrap. 29.2529 Section 29.2529 Agriculture...-Cured Tobacco (u.s. Types 22, 23, and Foreign Type 96) § 29.2529 Leaf scrap. A byproduct of unstemmed tobacco. Leaf scrap results from handling unstemmed tobacco and consists of loose and tangled whole or...

  12. 7 CFR 29.3526 - Leaf scrap.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Leaf scrap. 29.3526 Section 29.3526 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing... Type 95) § 29.3526 Leaf scrap. A byproduct of unstemmed tobacco Leaf scrap results from handling...

  13. 7 CFR 29.6022 - Leaf scrap.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 7 Agriculture 2 2011-01-01 2011-01-01 false Leaf scrap. 29.6022 Section 29.6022 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing... INSPECTION Standards Definitions § 29.6022 Leaf scrap. A byproduct of unstemmed tobacco Leaf scrap results...

  14. Peach leaf responses to soil and cement dust pollution.

    PubMed

    Maletsika, Persefoni A; Nanos, George D; Stavroulakis, George G

    2015-10-01

    Dust pollution can negatively affect plant productivity in hot, dry and with high irradiance areas during summer. Soil or cement dust were applied on peach trees growing in a Mediterranean area with the above climatic characteristics. Soil and cement dust accumulation onto the leaves decreased the photosynthetically active radiation (PAR) available to the leaves without causing any shade effect. Soil and mainly cement dust deposition onto the leaves decreased stomatal conductance, photosynthetic and transpiration rates, and water use efficiency due possibly to stomatal blockage and other leaf cellular effects. In early autumn, rain events removed soil dust and leaf functions partly recovered, while cement dust created a crust partially remaining onto the leaves and causing more permanent stress. Leaf characteristics were differentially affected by the two dusts studied due to their different hydraulic properties. Leaf total chlorophyll decreased and total phenol content increased with dust accumulation late in the summer compared to control leaves due to intense oxidative stress. The two dusts did not cause serious metal imbalances to the leaves, except of lower leaf K content.

  15. Comparison of half and full-leaf shape feature extraction for leaf classification

    NASA Astrophysics Data System (ADS)

    Sainin, Mohd Shamrie; Ahmad, Faudziah; Alfred, Rayner

    2016-08-01

    Shape is the main information for leaf feature that most of the current literatures in leaf identification utilize the whole leaf for feature extraction and to be used in the leaf identification process. In this paper, study of half-leaf features extraction for leaf identification is carried out and the results are compared with the results obtained from the leaf identification based on a full-leaf features extraction. Identification and classification is based on shape features that are represented as cosines and sinus angles. Six single classifiers obtained from WEKA and seven ensemble methods are used to compare their performance accuracies over this data. The classifiers were trained using 65 leaves in order to classify 5 different species of preliminary collection of Malaysian medicinal plants. The result shows that half-leaf features extraction can be used for leaf identification without decreasing the predictive accuracy.

  16. Pressure Actuated Leaf Seals for Improved Turbine Shaft Sealing

    NASA Technical Reports Server (NTRS)

    Grondahl, Clayton

    2006-01-01

    This presentation introduces a shaft seal in which leaf seal elements are constructed from slotted shim material formed and layered into a frusto-conical assembly. Limited elastic deflection of seal leaves with increasing system pressure close large startup clearance to a small, non-contacting, steady state running clearance. At shutdown seal elements resiliently retract as differential seal pressure diminishes. Large seal clearance during startup and shutdown provides a mechanism for rub avoidance. Minimum operating clearance improves performance and non-contacting operation promises long seal life. Design features of this seal, sample calculations at differential pressures up to 2400 psid and benefit comparison with brush and labyrinth seals is documented in paper, AIAA 2005 3985, presented at the Advanced Seal Technology session of the Joint Propulsion Conference in Tucson this past July. In this presentation use of bimetallic leaf material will be discussed. Frictional heating of bimetallic leaf seals during a seal rub can relieve the rub condition to some extent with a change in seal shape. Improved leaf seal rub tolerance is expected with bimetallic material.

  17. 7 CFR 29.1162 - Leaf (B Group).

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... Specifications, and Tolerances B1L—Choice Quality Lemon Leaf Ripe, firm leaf structure, medium body, rich in oil... percent. B2L—Fine Quality Lemon Leaf Ripe, firm leaf structure, medium body, rich in oil, deep color.... B3L—Good Quality Lemon Leaf Ripe, firm leaf structure, medium body, oily, strong color intensity...

  18. 7 CFR 29.1162 - Leaf (B Group).

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... Specifications, and Tolerances B1L—Choice Quality Lemon Leaf Ripe, firm leaf structure, medium body, rich in oil... percent. B2L—Fine Quality Lemon Leaf Ripe, firm leaf structure, medium body, rich in oil, deep color.... B3L—Good Quality Lemon Leaf Ripe, firm leaf structure, medium body, oily, strong color intensity...

  19. 7 CFR 29.1162 - Leaf (B Group).

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... Specifications, and Tolerances B1L—Choice Quality Lemon Leaf Ripe, firm leaf structure, medium body, rich in oil... percent. B2L—Fine Quality Lemon Leaf Ripe, firm leaf structure, medium body, rich in oil, deep color.... B3L—Good Quality Lemon Leaf Ripe, firm leaf structure, medium body, oily, strong color intensity...

  20. 7 CFR 29.1162 - Leaf (B Group).

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... Specifications, and Tolerances B1L—Choice Quality Lemon Leaf Ripe, firm leaf structure, medium body, rich in oil... percent. B2L—Fine Quality Lemon Leaf Ripe, firm leaf structure, medium body, rich in oil, deep color.... B3L—Good Quality Lemon Leaf Ripe, firm leaf structure, medium body, oily, strong color intensity...

  1. 7 CFR 29.3648 - Thin Leaf (C Group).

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... tolerance. C4L Fair Quality Light-brown Thin Leaf. Mature, thin, close leaf structure, rough, lean in oil... tolerance. C5L Low Quality Light-brown Thin Leaf Underripe, thin, close leaf structure, rough, lean in oil... tolerance. C4F Fair Quality Medium-brown Thin Leaf. Mature, thin, close leaf structure, rough, lean in oil...

  2. 7 CFR 29.1162 - Leaf (B Group).

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... Specifications, and Tolerances B1L—Choice Quality Lemon Leaf Ripe, firm leaf structure, medium body, rich in oil... percent. B2L—Fine Quality Lemon Leaf Ripe, firm leaf structure, medium body, rich in oil, deep color.... B3L—Good Quality Lemon Leaf Ripe, firm leaf structure, medium body, oily, strong color intensity...

  3. 7 CFR 29.3648 - Thin Leaf (C Group).

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... specifications, and tolerances C1L Choice Quality Light-brown Thin Leaf. Ripe, thin, open leaf structure, smooth... injury tolerance. C2L Fine Quality Light-brown Thin Leaf. Ripe, thin, open leaf structure, smooth, oily... tolerance. C1F Choice Quality Medium-brown Thin Leaf. Ripe, thin, open leaf structure, smooth, rich in oil...

  4. 7 CFR 29.3648 - Thin Leaf (C Group).

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... specifications, and tolerances C1L Choice Quality Light-brown Thin Leaf. Ripe, thin, open leaf structure, smooth... injury tolerance. C2L Fine Quality Light-brown Thin Leaf. Ripe, thin, open leaf structure, smooth, oily... tolerance. C1F Choice Quality Medium-brown Thin Leaf. Ripe, thin, open leaf structure, smooth, rich in oil...

  5. 7 CFR 29.3648 - Thin Leaf (C Group).

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... specifications, and tolerances C1L Choice Quality Light-brown Thin Leaf. Ripe, thin, open leaf structure, smooth... injury tolerance. C2L Fine Quality Light-brown Thin Leaf. Ripe, thin, open leaf structure, smooth, oily... tolerance. C1F Choice Quality Medium-brown Thin Leaf. Ripe, thin, open leaf structure, smooth, rich in oil...

  6. SPAD-based leaf nitrogen estimation is impacted by environmental factors and crop leaf characteristics

    PubMed Central

    Xiong, Dongliang; Chen, Jia; Yu, Tingting; Gao, Wanlin; Ling, Xiaoxia; Li, Yong; Peng, Shaobing; Huang, Jianliang

    2015-01-01

    Chlorophyll meters are widely used to guide nitrogen (N) management by monitoring leaf N status in agricultural systems, but the effects of environmental factors and leaf characteristics on leaf N estimations are still unclear. In the present study, we estimated the relationships among SPAD readings, chlorophyll content and leaf N content per leaf area for seven species grown in multiple environments. There were similar relationships between SPAD readings and chlorophyll content per leaf area for the species groups, but the relationship between chlorophyll content and leaf N content per leaf area, and the relationship between SPAD readings and leaf N content per leaf area varied widely among the species groups. A significant impact of light-dependent chloroplast movement on SPAD readings was observed under low leaf N supplementation in both rice and soybean but not under high N supplementation. Furthermore, the allocation of leaf N to chlorophyll was strongly influenced by short-term changes in growth light. We demonstrate that the relationship between SPAD readings and leaf N content per leaf area is profoundly affected by environmental factors and leaf features of crop species, which should be accounted for when using a chlorophyll meter to guide N management in agricultural systems. PMID:26303807

  7. Habitat Complexity of Stream Leaf Packs: Effects on Benthic Macroinvertebrates and Leaf Litter Breakdown

    NASA Astrophysics Data System (ADS)

    Ruetz, C. R.; Vanhaitsma, D. L.; Breen, M. J.

    2005-05-01

    We investigated two attributes of leaf-pack complexity (i.e., leaf-pack mass and leaf surface area) on fish predation, colonization of benthic macroinvertebrates, and leaf breakdown rates in a coldwater Michigan stream. We manipulated three factors using a factorial design: fish (exclusion or control cage), leaf-pack mass (1, 3, or 5 g dry mass), and leaf surface area (<7, 7-10, or >10 cm leaf width). Acer leaves were fastened into leaf packs. Exclusion cages had mesh on all sides; control cages lacked mesh on two sides to provide access to fishes. Two replicate leaf packs were randomly collected after 25-31 d from two sections of the stream (n = 4). Common shredders were Gammarus, Pycnopsyche, and Lepidostoma. We did not detect a significant effect of fish predation on benthic macroinvertebrates or leaf breakdown (i.e., mass loss). Colonization of benthic macroinvertebrates appeared proportional to leaf-pack mass but was unaffected by the surface area of leaves. Leaf breakdown was more rapid among leaf packs with fewer leaves (i.e., leaves with large surface area and leaf packs with low mass) and greater numbers of shredders. We suspect that physical fragmentation is the primary mechanism for higher breakdown rates among leaf packs with fewer leaves.

  8. Hormonal regulation of leaf senescence in Lilium.

    PubMed

    Arrom, Laia; Munné-Bosch, Sergi

    2012-10-15

    In addition to floral senescence and longevity, the control of leaf senescence is a major factor determining the quality of several cut flowers, including Lilium, in the commercial market. To better understand the physiological process underlying leaf senescence in this species, we evaluated: (i) endogenous variation in the levels of phytohormones during leaf senescence, (ii) the effects of leaf darkening in senescence and associated changes in phytohormones, and (iii) the effects of spray applications of abscisic acid (ABA) and pyrabactin on leaf senescence. Results showed that while gibberellin 4 (GA(4)) and salicylic acid (SA) contents decreased, that of ABA increased during the progression of leaf senescence. However, dark-induced senescence increased ABA levels, but did not affect GA(4) and SA levels, which appeared to correlate more with changes in air temperature and/or photoperiod than with the induction of leaf senescence. Furthermore, spray applications of pyrabactin delayed the progression of leaf senescence in cut flowers. Thus, we conclude that (i) ABA plays a major role in the regulation of leaf senescence in Lilium, (ii) darkness promotes leaf senescence and increases ABA levels, and (iii) exogenous applications of pyrabactin inhibit leaf senescence in Lilium, therefore suggesting that it acts as an antagonist of ABA in senescing leaves of cut lily flowers.

  9. Global climatic drivers of leaf size.

    PubMed

    Wright, Ian J; Dong, Ning; Maire, Vincent; Prentice, I Colin; Westoby, Mark; Díaz, Sandra; Gallagher, Rachael V; Jacobs, Bonnie F; Kooyman, Robert; Law, Elizabeth A; Leishman, Michelle R; Niinemets, Ülo; Reich, Peter B; Sack, Lawren; Villar, Rafael; Wang, Han; Wilf, Peter

    2017-09-01

    Leaf size varies by over a 100,000-fold among species worldwide. Although 19th-century plant geographers noted that the wet tropics harbor plants with exceptionally large leaves, the latitudinal gradient of leaf size has not been well quantified nor the key climatic drivers convincingly identified. Here, we characterize worldwide patterns in leaf size. Large-leaved species predominate in wet, hot, sunny environments; small-leaved species typify hot, sunny environments only in arid conditions; small leaves are also found in high latitudes and elevations. By modeling the balance of leaf energy inputs and outputs, we show that daytime and nighttime leaf-to-air temperature differences are key to geographic gradients in leaf size. This knowledge can enrich "next-generation" vegetation models in which leaf temperature and water use during photosynthesis play key roles. Copyright © 2017, American Association for the Advancement of Science.

  10. The relationship of leaf photosynthetic traits V cmax and Jmax - to leaf nitrogen, leaf phosphorus, and specific leaf area: A meta-analysis and modeling study

    SciTech Connect

    Walker, Anthony P.; Beckerman, Andrew P.; Gu, Lianhong; Kattge, Jens; Cernusak, Lucas A.; Domingues, Tomas F.; Scales, Joanna C.; Wohlfahrt, Georg; Wullschleger, Stan D.; Woodward, F. Ian

    2014-07-25

    Great uncertainty exists in the global exchange of carbon between the atmosphere and the terrestrial biosphere. An important source of this uncertainty lies in the dependency of photosynthesis on the maximum rate of carboxylation (Vcmax) and the maximum rate of electron transport (Jmax). Understanding and making accurate prediction of C fluxes thus requires accurate characterization of these rates and their relationship with plant nutrient status over large geographic scales. Plant nutrient status is indicated by the traits: leaf nitrogen (N), leaf phosphorus (P), and specific leaf area (SLA). Correlations between Vcmax and Jmax and leaf nitrogen (N) are typically derived from local to global scales, while correlations with leaf phosphorus (P) and specific leaf area (SLA) have typically been derived at a local scale. Thus, there is no global-scale relationship between Vcmax and Jmax and P or SLA limiting the ability of global-scale carbon flux models do not account for P or SLA. We gathered published data from 24 studies to reveal global relationships of Vcmax and Jmax with leaf N, P, and SLA. Vcmax was strongly related to leaf N, and increasing leaf P substantially increased the sensitivity of Vcmax to leaf N. Jmax was strongly related to Vcmax, and neither leaf N, P, or SLA had a substantial impact on the relationship. Although more data are needed to expand the applicability of the relationship, we show leaf P is a globally important determinant of photosynthetic rates. In a model of photosynthesis, we showed that at high leaf N (3 gm 2), increasing leaf P from 0.05 to 0.22 gm 2 nearly doubled assimilation rates. Lastly, we show that plants may employ a conservative strategy of Jmax to Vcmax coordination that restricts photoinhibition when carboxylation is limiting at the expense of maximizing photosynthetic rates when light is limiting.

  11. The relationship of leaf photosynthetic traits V cmax and Jmax - to leaf nitrogen, leaf phosphorus, and specific leaf area: A meta-analysis and modeling study

    DOE PAGES

    Walker, Anthony P.; Beckerman, Andrew P.; Gu, Lianhong; ...

    2014-07-25

    Great uncertainty exists in the global exchange of carbon between the atmosphere and the terrestrial biosphere. An important source of this uncertainty lies in the dependency of photosynthesis on the maximum rate of carboxylation (Vcmax) and the maximum rate of electron transport (Jmax). Understanding and making accurate prediction of C fluxes thus requires accurate characterization of these rates and their relationship with plant nutrient status over large geographic scales. Plant nutrient status is indicated by the traits: leaf nitrogen (N), leaf phosphorus (P), and specific leaf area (SLA). Correlations between Vcmax and Jmax and leaf nitrogen (N) are typically derivedmore » from local to global scales, while correlations with leaf phosphorus (P) and specific leaf area (SLA) have typically been derived at a local scale. Thus, there is no global-scale relationship between Vcmax and Jmax and P or SLA limiting the ability of global-scale carbon flux models do not account for P or SLA. We gathered published data from 24 studies to reveal global relationships of Vcmax and Jmax with leaf N, P, and SLA. Vcmax was strongly related to leaf N, and increasing leaf P substantially increased the sensitivity of Vcmax to leaf N. Jmax was strongly related to Vcmax, and neither leaf N, P, or SLA had a substantial impact on the relationship. Although more data are needed to expand the applicability of the relationship, we show leaf P is a globally important determinant of photosynthetic rates. In a model of photosynthesis, we showed that at high leaf N (3 gm 2), increasing leaf P from 0.05 to 0.22 gm 2 nearly doubled assimilation rates. Lastly, we show that plants may employ a conservative strategy of Jmax to Vcmax coordination that restricts photoinhibition when carboxylation is limiting at the expense of maximizing photosynthetic rates when light is limiting.« less

  12. The relationship of leaf photosynthetic traits - V cmax and J max - to leaf nitrogen, leaf phosphorus, and specific leaf area: a meta-analysis and modeling study.

    PubMed

    Walker, Anthony P; Beckerman, Andrew P; Gu, Lianhong; Kattge, Jens; Cernusak, Lucas A; Domingues, Tomas F; Scales, Joanna C; Wohlfahrt, Georg; Wullschleger, Stan D; Woodward, F Ian

    2014-08-01

    Great uncertainty exists in the global exchange of carbon between the atmosphere and the terrestrial biosphere. An important source of this uncertainty lies in the dependency of photosynthesis on the maximum rate of carboxylation (V cmax) and the maximum rate of electron transport (J max). Understanding and making accurate prediction of C fluxes thus requires accurate characterization of these rates and their relationship with plant nutrient status over large geographic scales. Plant nutrient status is indicated by the traits: leaf nitrogen (N), leaf phosphorus (P), and specific leaf area (SLA). Correlations between V cmax and J max and leaf nitrogen (N) are typically derived from local to global scales, while correlations with leaf phosphorus (P) and specific leaf area (SLA) have typically been derived at a local scale. Thus, there is no global-scale relationship between V cmax and J max and P or SLA limiting the ability of global-scale carbon flux models do not account for P or SLA. We gathered published data from 24 studies to reveal global relationships of V cmax and J max with leaf N, P, and SLA. V cmax was strongly related to leaf N, and increasing leaf P substantially increased the sensitivity of V cmax to leaf N. J max was strongly related to V cmax, and neither leaf N, P, or SLA had a substantial impact on the relationship. Although more data are needed to expand the applicability of the relationship, we show leaf P is a globally important determinant of photosynthetic rates. In a model of photosynthesis, we showed that at high leaf N (3 gm(-2)), increasing leaf P from 0.05 to 0.22 gm(-2) nearly doubled assimilation rates. Finally, we show that plants may employ a conservative strategy of J max to V cmax coordination that restricts photoinhibition when carboxylation is limiting at the expense of maximizing photosynthetic rates when light is limiting.

  13. The relationship of leaf photosynthetic traits – Vcmax and Jmax – to leaf nitrogen, leaf phosphorus, and specific leaf area: a meta-analysis and modeling study

    PubMed Central

    Walker, Anthony P; Beckerman, Andrew P; Gu, Lianhong; Kattge, Jens; Cernusak, Lucas A; Domingues, Tomas F; Scales, Joanna C; Wohlfahrt, Georg; Wullschleger, Stan D; Woodward, F Ian

    2014-01-01

    Great uncertainty exists in the global exchange of carbon between the atmosphere and the terrestrial biosphere. An important source of this uncertainty lies in the dependency of photosynthesis on the maximum rate of carboxylation (Vcmax) and the maximum rate of electron transport (Jmax). Understanding and making accurate prediction of C fluxes thus requires accurate characterization of these rates and their relationship with plant nutrient status over large geographic scales. Plant nutrient status is indicated by the traits: leaf nitrogen (N), leaf phosphorus (P), and specific leaf area (SLA). Correlations between Vcmax and Jmax and leaf nitrogen (N) are typically derived from local to global scales, while correlations with leaf phosphorus (P) and specific leaf area (SLA) have typically been derived at a local scale. Thus, there is no global-scale relationship between Vcmax and Jmax and P or SLA limiting the ability of global-scale carbon flux models do not account for P or SLA. We gathered published data from 24 studies to reveal global relationships of Vcmax and Jmax with leaf N, P, and SLA. Vcmax was strongly related to leaf N, and increasing leaf P substantially increased the sensitivity of Vcmax to leaf N. Jmax was strongly related to Vcmax, and neither leaf N, P, or SLA had a substantial impact on the relationship. Although more data are needed to expand the applicability of the relationship, we show leaf P is a globally important determinant of photosynthetic rates. In a model of photosynthesis, we showed that at high leaf N (3 gm−2), increasing leaf P from 0.05 to 0.22 gm−2 nearly doubled assimilation rates. Finally, we show that plants may employ a conservative strategy of Jmax to Vcmax coordination that restricts photoinhibition when carboxylation is limiting at the expense of maximizing photosynthetic rates when light is limiting. PMID:25473475

  14. Environmental modification of yield and nutrient composition of 'Waldmann's Green' leaf lettuce

    NASA Technical Reports Server (NTRS)

    Mitchell, C. A.; Chun, C.; Brandt, W. E.; Nielsen, S. S.

    1997-01-01

    Leaf number, dry weight, and nutrient composition of Lactuca sativa L. cv. Waldmann's Green leaves were compared following 9 days of treatment in a controlled environment room under various combinations of photosynthetic photon flux (PPF:350 vs 800 micromoles m-2 s-1), atmospheric CO2 level (ambient vs 1500 micromoles mol-1), and single-strength (1X:15 mM) vs double-strength (2X:30 mM) nitrogen (N) as NO3- alone or as NH4(+) + NO3- (1:5 molar ratio). CO2 enrichment greatly enhanced leaf number under all PPF and N conditions, but increased leaf dry weight only at high PPF. Conditions favoring high photosynthesis enhanced leaf starch content 3-fold, and protein content increased as much as 64% with 2X NH4(+)+NO3-. Free sugar content was 6 to 9% of leaf dry weight for all treatment combinations, while fat was 1.5 to 3.5%. Ash content varied from 15 to 20% of leaf dry weight. Modified controlled environments can be used to enhance the nutritional content as well as the yield of crops to be used for life support in space-deployed, self-sustaining human habitats. Leaf lettuce is a useful model crop for demonstrating the potential of nutritional value added by environmental manipulation.

  15. Environmental modification of yield and nutrient composition of 'Waldmann's Green' leaf lettuce

    NASA Technical Reports Server (NTRS)

    Mitchell, C. A.; Chun, C.; Brandt, W. E.; Nielsen, S. S.

    1997-01-01

    Leaf number, dry weight, and nutrient composition of Lactuca sativa L. cv. Waldmann's Green leaves were compared following 9 days of treatment in a controlled environment room under various combinations of photosynthetic photon flux (PPF:350 vs 800 micromoles m-2 s-1), atmospheric CO2 level (ambient vs 1500 micromoles mol-1), and single-strength (1X:15 mM) vs double-strength (2X:30 mM) nitrogen (N) as NO3- alone or as NH4(+) + NO3- (1:5 molar ratio). CO2 enrichment greatly enhanced leaf number under all PPF and N conditions, but increased leaf dry weight only at high PPF. Conditions favoring high photosynthesis enhanced leaf starch content 3-fold, and protein content increased as much as 64% with 2X NH4(+)+NO3-. Free sugar content was 6 to 9% of leaf dry weight for all treatment combinations, while fat was 1.5 to 3.5%. Ash content varied from 15 to 20% of leaf dry weight. Modified controlled environments can be used to enhance the nutritional content as well as the yield of crops to be used for life support in space-deployed, self-sustaining human habitats. Leaf lettuce is a useful model crop for demonstrating the potential of nutritional value added by environmental manipulation.

  16. Leaf nitrogen and phosphorus stoichiometry across 753 terrestrial plant species in China.

    PubMed

    Han, Wenxuan; Fang, Jingyun; Guo, Dali; Zhang, Yan

    2005-11-01

    Leaf nitrogen and phosphorus stoichiometry of Chinese terrestrial plants was studied based on a national data set including 753 species across the country. Geometric means were calculated for functional groups based on life form, phylogeny and photosynthetic pathway, as well as for all 753 species. The relationships between leaf N and P stoichiometric traits and latitude (and temperature) were analysed. The geometric means of leaf N, P, and N : P ratio for the 753 species were 18.6 and 1.21 mg g(-1) and 14.4, respectively. With increasing latitude (decreasing mean annual temperature, MAT), leaf N and P increased, but the N : P ratio did not show significant changes. Although patterns of leaf N, P and N : P ratios across the functional groups were generally consistent with those reported previously, the overall N : P ratio of China's flora was considerably higher than the global averages, probably caused by a greater shortage of soil P in China than elsewhere. The relationships between leaf N, P and N : P ratio and latitude (and MAT) also suggested the existence of broad biogeographical patterns of these leaf traits in Chinese flora.

  17. Leaf architectural, vascular and photosynthetic acclimation to temperature in two biennials.

    PubMed

    Muller, Onno; Stewart, Jared J; Cohu, Christopher M; Polutchko, Stephanie K; Demmig-Adams, Barbara; Adams, William W

    2014-12-01

    Acclimation of leaf features to growth temperature was investigated in two biennials (whose life cycle spans summer and winter seasons) using different mechanisms of sugar loading into exporting conduits, Verbascum phoeniceum (employs sugar-synthesizing enzymes driving symplastic loading through plasmodesmatal wall pores of phloem cells) and Malva neglecta (likely apoplastic loader transporting sugar via membrane transport proteins of phloem cells). In both species, acclimation to lower temperature involved greater maximal photosynthesis rates and vein density per leaf area in close correlation with modification of minor vein cellular features. While the symplastically loading biennial exhibited adjustments in the size of minor leaf vein cells (consistent with adjustment of the level of sugar-synthesizing enzymes), the putative apoplastic biennial exhibited adjustments in the number of cells (consistent with adjustment of cell membrane area for transporter placement). This upregulation of morphological and anatomical features at lower growth temperature likely contributes to the success of both the species during the winter. Furthermore, while acclimation to low temperature involved greater leaf mass per area in both species, this resulted from greater leaf thickness in V. phoeniceum vs a greater number of mesophyll cells per leaf area in M. neglecta. Both types of adjustments presumably accommodate more chloroplasts per leaf area contributing to photosynthesis. Both biennials exhibited high foliar vein densities (particularly the solar-tracking M. neglecta), which should aid both sugar export from and delivery of water to the leaves. © 2014 Scandinavian Plant Physiology Society.

  18. High-Throughput and Computational Study of Leaf Senescence through a Phenomic Approach

    PubMed Central

    Lyu, Jae IL; Baek, Seung Hee; Jung, Sukjoon; Chu, Hyosub; Nam, Hong Gil; Kim, Jeongsik; Lim, Pyung Ok

    2017-01-01

    Leaf senescence is influenced by its life history, comprising a series of developmental and physiological experiences. Exploration of the biological principles underlying leaf lifespan and senescence requires a schema to trace leaf phenotypes, based on the interaction of genetic and environmental factors. We developed a new approach and concept that will facilitate systemic biological understanding of leaf lifespan and senescence, utilizing the phenome high-throughput investigator (PHI) with a single-leaf-basis phenotyping platform. Our pilot tests showed empirical evidence for the feasibility of PHI for quantitative measurement of leaf senescence responses and improved performance in order to dissect the progression of senescence triggered by different senescence-inducing factors as well as genetic mutations. Such an establishment enables new perspectives to be proposed, which will be challenged for enhancing our fundamental understanding on the complex process of leaf senescence. We further envision that integration of phenomic data with other multi-omics data obtained from transcriptomic, proteomic, and metabolic studies will enable us to address the underlying principles of senescence, passing through different layers of information from molecule to organism. PMID:28280501

  19. Light drives vertical gradients of leaf morphology in a sugar maple (Acer saccharum) forest.

    PubMed

    Coble, Adam P; Cavaleri, Molly A

    2014-02-01

    Leaf mass per area (LMA, g m(-2)) is an essential trait for modeling canopy function due to its strong association with photosynthesis, respiration and leaf nitrogen. Leaf mass per area, which is influenced by both leaf thickness and density (LMA = thickness × density), generally increases from the bottom to the top of tree canopies, yet the mechanisms behind this universal pattern are not yet resolved. For decades, the light environment was assumed to be the most influential driver of within-canopy variation in LMA, yet recent evidence has shown hydrostatic gradients to be more important in upper canopy positions, especially in tall evergreen trees in temperate and tropical forests. The aim of this study was to disentangle the importance of various environmental drivers on vertical LMA gradients in a mature sugar maple (Acer saccharum Marshall) forest. We compared LMA, leaf density and leaf thickness relationships with height, light and predawn leaf water potential (ΨPre) within a closed and an exposed canopy to assess leaf morphological traits at similar heights but different light conditions. Contrary to our expectations and recent findings in the literature, we found strong evidence that light was the primary driver of vertical gradients in leaf morphology. At similar heights (13-23 m), LMA was greater within the exposed canopy than the closed canopy, and light had a stronger influence over LMA compared with ΨPre. Light also had a stronger influence over both leaf thickness and density compared with ΨPre; however, the increase in LMA within both canopy types was primarily due to increasing leaf thickness with increasing light availability. This study provides strong evidence that canopy structure and crown exposure, in addition to height, should be considered as a parameter for determining vertical patterns in LMA and modeling canopy function.

  20. Leaf hydraulic conductance is coordinated with leaf morpho-anatomical traits and nitrogen status in the genus Oryza.

    PubMed

    Xiong, Dongliang; Yu, Tingting; Zhang, Tong; Li, Yong; Peng, Shaobing; Huang, Jianliang

    2015-02-01

    Leaf hydraulic conductance (K leaf) is a major determinant of photosynthetic rate in plants. Previous work has assessed the relationships between leaf morpho-anatomical traits and K leaf with woody species, but there has been very little focus on cereal crops. The genus Oryza, which includes rice (Oryza sativa) and wild species (such as O. rufipogon cv. Griff), is ideal material for identifying leaf features associated with K leaf and gas exchange. Leaf morpho-anatomical traits, K leaf, leaf N content per leaf area, and CO2 diffusion efficiency were investigated in 11 Oryza cultivars. K leaf was positively correlated with leaf thickness and related traits, and therefore positively correlated with leaf mass per area and leaf N content per leaf area, and negatively with inter-veinal distance. K leaf was also positively correlated with leaf area and its related traits, and therefore negatively correlated with the proportion of minor vein length per area. In addition, coordination between K leaf and CO2 diffusion conductance in leaves was observed. We conclude that leaf morpho-anatomical traits and N content per leaf area strongly influence K leaf. Our results suggest that more detailed anatomical and structural studies are needed to elucidate the impacts of leaf feature traits on K leaf and gas exchange in grasses.

  1. Yeasts colonizing the leaf surfaces.

    PubMed

    Sláviková, Elena; Vadkertiová, Renata; Vránová, Dana

    2007-08-01

    The yeasts were isolated from the leaf surfaces of ten species of trees. The study site was a forest park (Zelezná Studnicka) of the Small Carpathians mountain range. One hundred and thirty seven yeast strains belonging to 13 genera were isolated from 320 samples of leaves and needles. Seventeen yeast species were isolated, but only seven occurred regularly: Aureobasidium pullulans, Cryptococcus laurentii, Pichia anomala, Metschnikowia pulcherrima, Saccharomyces sp., Lachancea thermotolerans, and Rhodotorula glutinis. The remaining species were isolated from the leaves and needles of three or less tree species. A. pullulans, Cr. laurentii, and P. anomala were the most frequently found species and they occurred on leaves and needles of all ten tree species. Saccharomyces sp. occurred in leaf samples collected from eight kinds of trees. M. pulcherrima and L. thermotolerans were found in samples collected from six species of trees. Both these species occurred almost always on the leaves of deciduous trees. Rh. glutinis was the most frequently isolated carotenoids producing species. We have found out that the ascomycetous and basidiomycetous species were present in the leaf samples in approximately equal frequency, contrary to the soil samples taken from this forest park, where the ascomycetous species were found rarely.

  2. Cotton leaf curl virus disease.

    PubMed

    Briddon, R W; Markham, P G

    2000-11-01

    Cotton is one of the most important crops of Pakistan, accounting for over 60% of foreign exchange earnings. The present epidemic of cotton leaf curl disease (CLCuD) originated in the Punjab region near the city of Multan and was first reported in 1985, although it was noted in this region as early as 1967. By the early 1990s, CLCuD had become the major limitation to cotton production in Pakistan and it has now spread into India and, more recently, south and west into other provinces of Pakistan. The very characteristic symptoms include leaf curling, darkened veins, vein swelling and enations that frequently develop into cup-shaped, leaf-like structures on the undersides of leaves. Identification of the vector of CLCuD as the whitefly Bemisia tabaci (Genn.) quickly led to the suggestion that the causative agent of the disease is a geminivirus. Researchers soon confirmed the presence of such a virus that is currently ascribed to the genus Begomovirus of the family Geminiviridae, However, in 1999, the aetiology of the disease was shown to be more complex than was originally assumed. Despite the identification of both a begomovirus and a so-called nanovirus-like component, the precise causal agent of CLCuD remains uncertain.

  3. The importance of protein in leaf selection of folivorous primates.

    PubMed

    Ganzhorn, Joerg U; Arrigo-Nelson, Summer J; Carrai, Valentina; Chalise, Mukesh K; Donati, Giuseppe; Droescher, Iris; Eppley, Timothy M; Irwin, Mitchell T; Koch, Flávia; Koenig, Andreas; Kowalewski, Martin M; Mowry, Christopher B; Patel, Erik R; Pichon, Claire; Ralison, Jose; Reisdorff, Christoph; Simmen, Bruno; Stalenberg, Eleanor; Starrs, Danswell; Terboven, Juana; Wright, Patricia C; Foley, William J

    2016-04-19

    Protein limitation has been considered a key factor in hypotheses on the evolution of life history and animal communities, suggesting that animals should prioritize protein in their food choice. This contrasts with the limited support that food selection studies have provided for such a priority in nonhuman primates, particularly for folivores. Here, we suggest that this discrepancy can be resolved if folivores only need to select for high protein leaves when average protein concentration in the habitat is low. To test the prediction, we applied meta-analyses to analyze published and unpublished results of food selection for protein and fiber concentrations from 24 studies (some with multiple species) of folivorous primates. To counter potential methodological flaws, we differentiated between methods analyzing total nitrogen and soluble protein concentrations. We used a meta-analysis to test for the effect of protein on food selection by primates and found a significant effect of soluble protein concentrations, but a non-significant effect for total nitrogen. Furthermore, selection for soluble protein was reinforced in forests where protein was less available. Selection for low fiber content was significant but unrelated to the fiber concentrations in representative leaf samples of a given forest. There was no relationship (either negative or positive) between the concentration of protein and fiber in the food or in representative samples of leaves. Overall our study suggests that protein selection is influenced by the protein availability in the environment, explaining the sometimes contradictory results in previous studies on protein selection. Am. J. Primatol. © 2016 Wiley Periodicals, Inc.

  4. Convergence in relationships between leaf traits, spectra and age across diverse canopy environments and two contrasting tropical forests.

    PubMed

    Wu, Jin; Chavana-Bryant, Cecilia; Prohaska, Neill; Serbin, Shawn P; Guan, Kaiyu; Albert, Loren P; Yang, Xi; van Leeuwen, Willem J D; Garnello, Anthony John; Martins, Giordane; Malhi, Yadvinder; Gerard, France; Oliviera, Raimundo Cosme; Saleska, Scott R

    2017-05-01

    Leaf age structures the phenology and development of plants, as well as the evolution of leaf traits over life histories. However, a general method for efficiently estimating leaf age across forests and canopy environments is lacking. Here, we explored the potential for a statistical model, previously developed for Peruvian sunlit leaves, to consistently predict leaf ages from leaf reflectance spectra across two contrasting forests in Peru and Brazil and across diverse canopy environments. The model performed well for independent Brazilian sunlit and shade canopy leaves (R(2)  = 0.75-0.78), suggesting that canopy leaves (and their associated spectra) follow constrained developmental trajectories even in contrasting forests. The model did not perform as well for mid-canopy and understory leaves (R(2)  = 0.27-0.29), because leaves in different environments have distinct traits and trait developmental trajectories. When we accounted for distinct environment-trait linkages - either by explicitly including traits and environments in the model, or, even better, by re-parameterizing the spectra-only model to implicitly capture distinct trait-trajectories in different environments - we achieved a more general model that well-predicted leaf age across forests and environments (R(2)  = 0.79). Fundamental rules, linked to leaf environments, constrain the development of leaf traits and allow for general prediction of leaf age from spectra across species, sites and canopy environments.

  5. The Influence of Leaf Angle and Leaf Surface Characteristics on the Process of Rainfall Interception

    NASA Astrophysics Data System (ADS)

    Holder, C.; Ginebra, R.; Webb, R.

    2015-12-01

    Individual choice in plant selection for household landscaping influences differences in runoff from urban watersheds because the variation in plant canopy architecture results in rainfall interception differences. Understanding the variables that influence rainfall interception and understanding the mechanism of rainfall interception are important concepts for sustainable watershed management. The broad objective of this study was to explore the influence of leaf hydrophobicity, water droplet retention, and leaf angle on the mechanism and process of rainfall interception and raindrop impaction on leaf surfaces of common tree species from the semi-arid regions of the western United States. Leaf hydrophobicity is determined by the cohesive forces of the water molecules among themselves and the adhesive forces that result from the molecular interactions between the water droplet and the leaf surface. Water droplet retention is a measure of how easily a water droplet drains off a leaf surface. The specific hypotheses examined were 1) larger raindrops falling on leaf surfaces will deflect the leaf to an angle greater than the water droplet retention angle; 2) an increased leaf angle, whether from natural position or deflection due to droplet impact and retention, reduces interception from raindrop impaction on hydrophobic and hydrophilic leaf surfaces; and 3) increased droplet size and frequency decrease rainfall interception more significantly in the hydrophilic case. These hypotheses were addressed in a laboratory experiment by 1) measuring leaf hydrophobicity and water droplet retention using a goniometer with a tilting base; 2) measuring leaf traits such as leaf area, leaf surface roughness, trichome density, and specific storage capacity; 3) examining raindrop splash on leaf surfaces with varying leaf hydrophobicity, water droplet retention, and leaf angle with a raindrop generator and high-speed video camera; and 4) modeling the impact of raindrop splash on leaf

  6. A leaf-rolling weevil benefits from general saprophytic fungi in polysaccharide degradation

    USDA-ARS?s Scientific Manuscript database

    Insects form symbiosis with fungi widely, especially those feeding on leaf litter. As dead plant tissues provide poor quality diets which contain relatively high levels of indigestible lignin and cellulose, saprophytic fungi may increase nutrient availability by polysaccharide degradation. Although ...

  7. Leaf drop affects herbivory in oaks.

    PubMed

    Pearse, Ian S; Karban, Richard

    2013-11-01

    Leaf phenology is important to herbivores, but the timing and extent of leaf drop has not played an important role in our understanding of herbivore interactions with deciduous plants. Using phylogenetic general least squares regression, we compared the phenology of leaves of 55 oak species in a common garden with the abundance of leaf miners on those trees. Mine abundance was highest on trees with an intermediate leaf retention index, i.e. trees that lost most, but not all, of their leaves for 2-3 months. The leaves of more evergreen species were more heavily sclerotized, and sclerotized leaves accumulated fewer mines in the summer. Leaves of more deciduous species also accumulated fewer mines in the summer, and this was consistent with the idea that trees reduce overwintering herbivores by shedding leaves. Trees with a later leaf set and slower leaf maturation accumulated fewer herbivores. We propose that both leaf drop and early leaf phenology strongly affect herbivore abundance and select for differences in plant defense. Leaf drop may allow trees to dispose of their herbivores so that the herbivores must recolonize in spring, but trees with the longest leaf retention also have the greatest direct defenses against herbivores.

  8. Seedling growth and biomass allocation in relation to leaf habit and shade tolerance among 10 temperate tree species.

    PubMed

    Modrzyński, Jerzy; Chmura, Daniel J; Tjoelker, Mark G

    2015-08-01

    Initial growth of germinated seeds is an important life history stage, critical for establishment and succession in forests. Important questions remain regarding the differences among species in early growth potential arising from shade tolerance. In addition, the role of leaf habit in shaping relationships underlying shade tolerance-related differences in seedling growth remains unresolved. In this study we examined variation in morphological and physiological traits among seedlings of 10 forest tree species of the European temperate zone varying in shade tolerance and leaf habit (broadleaved winter-deciduous species vs needle-leaved conifers) during a 10-week period. Seeds were germinated and grown in a controlled environment simulating an intermediate forest understory light environment to resolve species differences in initial growth and biomass allocation. In the high-resource experimental conditions during the study, seedlings increased biomass allocation to roots at the cost of leaf biomass independent of shade tolerance and leaf habit. Strong correlations between relative growth rate (RGR), net assimilation rate (NAR), leaf area ratio (LAR), specific leaf area (SLA) and leaf mass fraction (LMF) indicate that physiology and biomass allocation were equally important determinants of RGR as plant structure and leaf morphology among these species. Our findings highlight the importance of seed mass- and seed size-related root morphology (specific root length-SRL) for shade tolerance during early ontogeny. Leaf and plant morphology (SLA, LAR) were more successful in explaining variation among species due to leaf habit than shade tolerance. In both broadleaves and conifers, shade-tolerant species had lower SRL and greater allocation of biomass to stems (stem mass fraction). Light-seeded shade-intolerant species with greater SRL had greater RGR in both leaf habit groups. However, the greatest plant mass was accumulated in the group of heavy-seeded shade

  9. The Leaf Size–Twig Size Spectrum of Temperate Woody Species Along an Altitudinal Gradient: An Invariant Allometric Scaling Relationship

    PubMed Central

    SUN, SHUCUN; JIN, DONGMEI; SHI, PEILI

    2006-01-01

    • Background and Aims The leaf size–twig size spectrum is one of the leading dimensions of plant ecological variation, and now it is under development. The purpose of this study was to test whether the relationship between leaf size and twig size is isometric or allometric, and to examine the relationship between plant allometric growth and life history strategies in the spectrum. • Methods Leaf and stem characters—including leaf and stem mass, total leaf area, individual leaf area, stem cross-sectional area, leaf number and stem length—at the twig level for 59 woody species were investigated along an altitudinal gradient on Changbaishan Mountain in the temperate zone of China. The environmental gradient ranges from temperate broad-leaved mixed forest at low altitude, to conifer forest at middle altitude, and to sub-alpine birch forest at high altitude. The scaling relationships between stem cross-sectional area and stem mass, stem mass and leaf mass, and leaf mass and leaf area at the twig level were simultaneously determined. • Key Results Twig cross-sectional area was found to have invariant allometric scaling relationships with the stem mass, leaf mass, total leaf area and individual leaf area, all with common slopes being significantly larger than 1, for three altitudinal-zoned vegetation types under investigation. However, leaf mass was found to be isometrically related to stem mass and leaf area along the environmental gradient. Based on the predictions of previous models, the exponent value of the relationship between twig cross-sectional area and total leaf area can be inferred to be 1·5, which falls between the confidence intervals of the relationship at each altitude, and between the confidence intervals of the common slope value (1·17–1·56) of this study. This invariant scaling relationship is assumed to result from the fractural network and/or developmental constraints of plants. The allometric constants (y-intercepts) of the

  10. Oxygen isotope fractionations across individual leaf carbohydrates in grass and tree species.

    PubMed

    Lehmann, Marco M; Gamarra, Bruno; Kahmen, Ansgar; Siegwolf, Rolf T W; Saurer, Matthias

    2017-08-01

    Almost no δ(18) O data are available for leaf carbohydrates, leaving a gap in the understanding of the δ(18) O relationship between leaf water and cellulose. We measured δ(18) O values of bulk leaf water (δ(18) OLW ) and individual leaf carbohydrates (e.g. fructose, glucose and sucrose) in grass and tree species and δ(18) O of leaf cellulose in grasses. The grasses were grown under two relative humidity (rH) conditions. Sucrose was generally (18) O-enriched compared with hexoses across all species with an apparent biosynthetic fractionation factor (εbio ) of more than 27‰ relative to δ(18) OLW , which might be explained by isotopic leaf water and sucrose synthesis gradients. δ(18) OLW and δ(18) O values of carbohydrates and cellulose in grasses were strongly related, indicating that the leaf water signal in carbohydrates was transferred to cellulose (εbio  = 25.1‰). Interestingly, damping factor pex px , which reflects oxygen isotope exchange with less enriched water during cellulose synthesis, responded to rH conditions if modelled from δ(18) OLW but not if modelled directly from δ(18) O of individual carbohydrates. We conclude that δ(18) OLW is not always a good substitute for δ(18) O of synthesis water due to isotopic leaf water gradients. Thus, compound-specific δ(18) O analyses of individual carbohydrates are helpful to better constrain (post-)photosynthetic isotope fractionation processes in plants. © 2017 John Wiley & Sons Ltd.

  11. Algorithm for retrieving vegetative canopy and leaf parameters from multi- and hyperspectral imagery

    NASA Astrophysics Data System (ADS)

    Borel, Christoph

    2009-05-01

    In recent years hyper-spectral data has been used to retrieve information about vegetative canopies such as leaf area index and canopy water content. For the environmental scientist these two parameters are valuable, but there is potentially more information to be gained as high spatial resolution data becomes available. We developed an Amoeba (Nelder-Mead or Simplex) based program to invert a vegetative canopy radiosity model coupled with a leaf (PROSPECT5) reflectance model and modeled for the background reflectance (e.g. soil, water, leaf litter) to a measured reflectance spectrum. The PROSPECT5 leaf model has five parameters: leaf structure parameter Nstru, chlorophyll a+b concentration Cab, carotenoids content Car, equivalent water thickness Cw and dry matter content Cm. The canopy model has two parameters: total leaf area index (LAI) and number of layers. The background reflectance model is either a single reflectance spectrum from a spectral library() derived from a bare area pixel on an image or a linear mixture of soil spectra. We summarize the radiosity model of a layered canopy and give references to the leaf/needle models. The method is then tested on simulated and measured data. We investigate the uniqueness, limitations and accuracy of the retrieved parameters on canopy parameters (low, medium and high leaf area index) spectral resolution (32 to 211 band hyperspectral), sensor noise and initial conditions.

  12. Leaf Extraction and Analysis Framework Graphical User Interface: Segmenting and Analyzing the Structure of Leaf Veins and Areoles1[W][OA

    PubMed Central

    Price, Charles A.; Symonova, Olga; Mileyko, Yuriy; Hilley, Troy; Weitz, Joshua S.

    2011-01-01

    Interest in the structure and function of physical biological networks has spurred the development of a number of theoretical models that predict optimal network structures across a broad array of taxonomic groups, from mammals to plants. In many cases, direct tests of predicted network structure are impossible given the lack of suitable empirical methods to quantify physical network geometry with sufficient scope and resolution. There is a long history of empirical methods to quantify the network structure of plants, from roots, to xylem networks in shoots and within leaves. However, with few exceptions, current methods emphasize the analysis of portions of, rather than entire networks. Here, we introduce the Leaf Extraction and Analysis Framework Graphical User Interface (LEAF GUI), a user-assisted software tool that facilitates improved empirical understanding of leaf network structure. LEAF GUI takes images of leaves where veins have been enhanced relative to the background, and following a series of interactive thresholding and cleaning steps, returns a suite of statistics and information on the structure of leaf venation networks and areoles. Metrics include the dimensions, position, and connectivity of all network veins, and the dimensions, shape, and position of the areoles they surround. Available for free download, the LEAF GUI software promises to facilitate improved understanding of the adaptive and ecological significance of leaf vein network structure. PMID:21057114

  13. Leaf economics of evergreen and deciduous tree species along an elevational gradient in a subtropical mountain

    PubMed Central

    Bai, Kundong; He, Chengxin; Wan, Xianchong; Jiang, Debing

    2015-01-01

    The ecophysiological mechanisms underlying the pattern of bimodal elevational distribution of evergreen tree species remain incompletely understood. Here we used leaf economics spectrum (LES) theory to explain such patterns. We measured leaf economic traits and constructed an LES for the co-existing 19 evergreen and 15 deciduous species growing in evergreen broad-leaved forest at low elevation, beech-mixed forest at middle elevation and hemlock-mixed forest at high elevation in Mao'er Mountain, Guangxi, Southern China (25°50′N, 110°49′E). Leaf economic traits presented low but significant phylogenetic signal, suggesting trait similarity between closely related species. After considering the effects of phylogenetic history, deciduous species in general showed a more acquisitive leaf strategy with a higher ratio of leaf water to dry mass, higher leaf nitrogen and phosphorous contents, higher photosynthetic and respiratory rates and greater photosynthetic nitrogen-use efficiency. In contrast, evergreen species exhibited a more conservative leaf strategy with higher leaf mass per area, greater construction costs and longer leaf life span. With the elevation-induced decreases of temperature and soil fertility, both evergreen and deciduous species showed greater resource conservation, suggesting the increasing importance of environmental filtering to community assembly with increasing elevation. We found close inter-specific correlations between leaf economic traits, suggesting that there are strong genetic constraints limiting the independent evolution of LES traits. Phylogenetic signal increased with decreasing evolutionary rate across leaf economic traits, suggesting that genetic constraints are important for the process of trait evolution. We found a significantly positive relationship between primary axis species score (PASS) distance and phylogenetic distance across species pairs and an increasing average PASS distance between evergreen and deciduous species

  14. 40 CFR 1042.815 - Demonstrating availability.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... available remanufacturing systems. A new remanufacturing system is considered to be available 120 days after... conventionally, divided by the projected amount that PM emissions will be reduced over the engine's useful life...) Incremental operating costs over one useful life period. (iv) Other costs (such as shipping). (2) Calculate...

  15. 40 CFR 1042.815 - Demonstrating availability.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... available remanufacturing systems. A new remanufacturing system is considered to be available 120 days after... conventionally, divided by the projected amount that PM emissions will be reduced over the engine's useful life...) Incremental operating costs over one useful life period. (iv) Other costs (such as shipping). (2) Calculate...

  16. Isotopic characteristics of canopies in simulated leaf assemblages

    NASA Astrophysics Data System (ADS)

    Graham, Heather V.; Patzkowsky, Mark E.; Wing, Scott L.; Parker, Geoffrey G.; Fogel, Marilyn L.; Freeman, Katherine H.

    2014-11-01

    The geologic history of closed-canopy forests is of great interest to paleoecologists and paleoclimatologists alike. Closed canopies have pronounced effects on local, continental and global rainfall and temperature patterns. Although evidence for canopy closure is difficult to reconstruct from the fossil record, the characteristic isotope gradients of the "canopy effect" could be preserved in leaves and proxy biomarkers. To assess this, we employed new carbon isotopic data for leaves collected in diverse light environments within a deciduous, temperate forest (Maryland, USA) and for leaves from a perennially closed canopy, moist tropical forest (Bosque Protector San Lorenzo, Panamá). In the tropical forest, leaf carbon isotope values range 10‰, with higher δ13Cleaf values occurring both in upper reaches of the canopy, and with higher light exposure and lower humidity. Leaf fractionation (Δleaf) varied negatively with height and light and positively with humidity. Vertical 13C enrichment in leaves largely reflects changes in Δleaf, and does not trend with δ13C of CO2 within the canopy. At the site in Maryland, leaves express a more modest δ13C range (∼6‰), with a clear trend that follows both light and leaf height. Using a model we simulate leaf assemblage isotope patterns from canopy data binned by elevation. The re-sampling (bootstrap) model determined both the mean and range of carbon isotope values for simulated leaf assemblages ranging in size from 10 to over 1000 leaves. For the tropical forest data, the canopy's isotope range is captured with 50 or more randomly sampled leaves. Thus, with a sufficient number of fossil leaves it is possible to distinguish isotopic gradients in an ancient closed canopy forest from those in an open forest. For very large leaf assemblages, mean isotopic values approximate the δ13C of carbon contributed by leaves to soil and are similar to observed δ13Clitter values at forested sites within Panamá, including the

  17. Leaf wax n-alkane δD values are determined early in the ontogeny of Populus trichocarpa leaves when grown under controlled environmental conditions.

    PubMed

    Kahmen, Ansgar; Dawson, Todd E; Vieth, Andrea; Sachse, Dirk

    2011-10-01

    The stable hydrogen isotope ratios (δD) of leaf wax n-alkanes record valuable information on plant and ecosystem water relations. It remains, however, unknown if leaf wax n-alkane δD values record only environmental variation during the brief period of time of leaf growth or if leaf wax n-alkane δD values are affected by environmental variability throughout the entire lifespan of a leaf. To resolve these uncertainties, we irrigated Populus trichocarpa trees with a pulse of deuterium-enriched water and used compound-specific stable hydrogen isotope analyses to test if the applied tracer could be recovered from leaf wax n-alkanes of leaves that were at different stages of their development during the tracer application. Our experiment revealed that only leaf wax n-alkanes from leaves that had developed during the time of the tracer application were affected, while leaves that were already fully matured at the time of the tracer application were not. We conclude from our study that under controlled environmental conditions, leaf wax n-alkanes are synthesized only early in the ontogeny of a leaf. Our experiment has implications for the interpretation of leaf wax n-alkane δD values in an environmental context, as it suggests that these compounds record only a brief period of the environmental variability that a leaf experiences throughout its life.

  18. From buds to litter: seasonal changes in leaf wax concentrations and carbon isotopes and implications for the geologic past

    NASA Astrophysics Data System (ADS)

    Suh, Y. J.; Diefendorf, A. F.

    2014-12-01

    The carbon isotope composition (δ13C) of leaf waxes, such as n-alkanes, have extensively been used in paleoenvironmental studies for reconstruction of the past vegetation, climate and carbon cycling. There is however little information available on the seasonal variation of leaf wax concentration and δ13C in modern plants and when the δ13C signal is set. This lack of information confounds interpretations of leaf wax δ13C in sedimentary archives. To address this gap, this study investigates temporal changes in n-alkane and n-alkanoic acid δ13C values in several species (Acer rubrum, Acer saccharum, Ulmus Americana, Sassafras albidum, and Juniperus virginiana) within a single temperate deciduous forest stand in southern Ohio. We sampled atmospheric air, buds, leaves, leaf litter, and surface soil weekly during leaf flush and biweekly thereafter. In A. rubrum, A. saccharum, and U. Americana, buds had one or two dominant n-alkanes, such as C29 and C31. After leaf flush, the concentrations of shorter n-alkanes (C23~C27) significantly increased relative to the longer chain-lengths. We are currently analyzing remaining samples from the growing season and are analyzing bulk leaf and leaf wax (n-alkanes, n-alkanoic acids) δ13C values. This information will be important for identifying environmental and physiological controls on leaf wax δ13C and will improve interpretations of leaf wax δ13C preserved in the geologic record.

  19. On the relationship between leaf photosynthetic capacity and leaf chlorophyll and implications for simulating GPP in space and time

    NASA Astrophysics Data System (ADS)

    Houborg, R.; Cescatti, A.; Migliavacca, M.

    2012-12-01

    Advancing the use of remote sensing data for retrieving key vegetation physiological controls is of critical importance for modeling spatio-temporal variations in gross primary productivity (GPP) with high fidelity. Key land-surface model controls on GPP, such as the maximum rate of carboxylation (Vcmax) that governs leaf photosynthetic efficiency, are typically assigned fixed literature-based values for broad categories of vegetation types although in reality temporal and spatial variability can be significant in response to differences in plant phenology and physiological condition, nutrient availability and climate. Vcmax defines the biochemical capacity of leaves to assimilate CO2 and is related to the nitrogen content of leaves, which is indirectly related to leaf reflectance and transmittance spectra. However, the fact that Vcmax is a leaf level parameter complicates larger scale parameterizations based on remote sensing observations due to confounding influences from the canopy and soil. Thus a key challenge is to separate the leaf contribution associated with changes in Vcmax from the total remote sensing signal. Chlorophylls are vital pigments for photosynthesis and directly controls leaf absorption in the visible waveband region. Here we report on the utility of satellite-based leaf chlorophyll (Chl) retrievals for quantifying Vcmax variability in space and time, and look into a mechanistic methodology for exploiting Chl information within the Community Land Model (CLM4) for improved predictability of GPP. Chl is retrieved from Landsat imagery by inversion of leaf optics and canopy reflectance models within the framework of REGFLEC (REGularized canopy reFLECtance tool). The potential of Chl retrievals for constraining model simulations of GPP is evaluated at multiple flux tower sites.ig. 1 Benefit of using satellite-based leaf chlorophyll (Chl) for parameterizing Vcmax and constraining modeled carbon fluxes over the growing season at a corn site in

  20. Classification and quantification of leaf curvature

    PubMed Central

    Liu, Zhongyuan; Jia, Liguo; Mao, Yanfei; He, Yuke

    2010-01-01

    Various mutants of Arabidopsis thaliana deficient in polarity, cell division, and auxin response are characterized by certain types of leaf curvature. However, comparison of curvature for clarification of gene function can be difficult without a quantitative measurement of curvature. Here, a novel method for classification and quantification of leaf curvature is reported. Twenty-two mutant alleles from Arabidopsis mutants and transgenic lines deficient in leaf flatness were selected. The mutants were classified according to the direction, axis, position, and extent of leaf curvature. Based on a global measure of whole leaves and a local measure of four regions in the leaves, the curvature index (CI) was proposed to quantify the leaf curvature. The CI values accounted for the direction, axis, position, and extent of leaf curvature in all of the Arabidopsis mutants grown in growth chambers. Comparison of CI values between mutants reveals the spatial and temporal variations of leaf curvature, indicating the strength of the mutant alleles and the activities of the corresponding genes. Using the curvature indices, the extent of curvature in a complicated genetic background becomes quantitative and comparable, thus providing a useful tool for defining the genetic components of leaf development and to breed new varieties with leaf curvature desirable for the efficient capture of sunlight for photosynthesis and high yields. PMID:20400533

  1. Classification and quantification of leaf curvature.

    PubMed

    Liu, Zhongyuan; Jia, Liguo; Mao, Yanfei; He, Yuke

    2010-06-01

    Various mutants of Arabidopsis thaliana deficient in polarity, cell division, and auxin response are characterized by certain types of leaf curvature. However, comparison of curvature for clarification of gene function can be difficult without a quantitative measurement of curvature. Here, a novel method for classification and quantification of leaf curvature is reported. Twenty-two mutant alleles from Arabidopsis mutants and transgenic lines deficient in leaf flatness were selected. The mutants were classified according to the direction, axis, position, and extent of leaf curvature. Based on a global measure of whole leaves and a local measure of four regions in the leaves, the curvature index (CI) was proposed to quantify the leaf curvature. The CI values accounted for the direction, axis, position, and extent of leaf curvature in all of the Arabidopsis mutants grown in growth chambers. Comparison of CI values between mutants reveals the spatial and temporal variations of leaf curvature, indicating the strength of the mutant alleles and the activities of the corresponding genes. Using the curvature indices, the extent of curvature in a complicated genetic background becomes quantitative and comparable, thus providing a useful tool for defining the genetic components of leaf development and to breed new varieties with leaf curvature desirable for the efficient capture of sunlight for photosynthesis and high yields.

  2. 7 CFR 30.2 - Leaf tobacco.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... stemming, sweating or fermenting, and conditioning are not regarded as manufacturing processes. Leaf tobacco does not include any manufactured or semimanufactured tobacco, stems which have been removed from...

  3. 7 CFR 30.2 - Leaf tobacco.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... stemming, sweating or fermenting, and conditioning are not regarded as manufacturing processes. Leaf tobacco does not include any manufactured or semimanufactured tobacco, stems which have been removed from...

  4. 7 CFR 30.2 - Leaf tobacco.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... stemming, sweating or fermenting, and conditioning are not regarded as manufacturing processes. Leaf tobacco does not include any manufactured or semimanufactured tobacco, stems which have been removed from...

  5. 7 CFR 30.2 - Leaf tobacco.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... stemming, sweating or fermenting, and conditioning are not regarded as manufacturing processes. Leaf tobacco does not include any manufactured or semimanufactured tobacco, stems which have been removed...

  6. 7 CFR 30.2 - Leaf tobacco.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... stemming, sweating or fermenting, and conditioning are not regarded as manufacturing processes. Leaf tobacco does not include any manufactured or semimanufactured tobacco, stems which have been removed...

  7. Salinity Effects on Leaf Anatomy

    PubMed Central

    Longstreth, David J.; Nobel, Park S.

    1979-01-01

    Increasing salinity led to substantially higher ratios of mesophyll surface area to leaf area (Ames/A) for Phaseolus vulgaris and Gossypium hirsutum and a smaller increase for Atriplex patula, a salt-tolerant species. The increase in internal surface for CO2 absorption did not lead to higher CO2 uptake rates, since the CO2 resistance expressed on the basis of mesophyll cell wall area (rcell) increased even more with salinity. The differences among species in the sensitivity of photosynthesis to salinity in part reflect the different Ames/A and rcell responses. PMID:16660795

  8. Transcriptional networks in leaf senescence.

    PubMed

    Schippers, Jos H M

    2015-10-01

    Plant senescence is a natural phenomenon known for the appearance of beautiful autumn colors and the ripening of cereals in the field. Senescence is a controlled process that plants utilize to remobilize nutrients from source leaves to developing tissues. While during the past decades, molecular components underlying the onset of senescence have been intensively studied, knowledge remains scarce on the age-dependent mechanisms that control the onset of senescence. Recent advances have uncovered transcriptional networks regulating the competence to senesce. Here, gene regulatory networks acting as internal timing mechanisms for the onset of senescence are highlighted, illustrating that early and late leaf developmental phases are highly connected.

  9. 7 CFR 28.471 - Below Leaf Grade Cotton.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 7 Agriculture 2 2012-01-01 2012-01-01 false Below Leaf Grade Cotton. 28.471 Section 28.471... REGULATIONS COTTON CLASSING, TESTING, AND STANDARDS Standards Below Leaf Grade Cotton § 28.471 Below Leaf Grade Cotton. Below leaf grade cotton is American Upland cotton which is lower in leaf grade than...

  10. 7 CFR 28.471 - Below Leaf Grade Cotton.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 7 Agriculture 2 2011-01-01 2011-01-01 false Below Leaf Grade Cotton. 28.471 Section 28.471... REGULATIONS COTTON CLASSING, TESTING, AND STANDARDS Standards Below Leaf Grade Cotton § 28.471 Below Leaf Grade Cotton. Below leaf grade cotton is American Upland cotton which is lower in leaf grade than...

  11. 7 CFR 28.471 - Below Leaf Grade Cotton.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 7 Agriculture 2 2013-01-01 2013-01-01 false Below Leaf Grade Cotton. 28.471 Section 28.471... REGULATIONS COTTON CLASSING, TESTING, AND STANDARDS Standards Below Leaf Grade Cotton § 28.471 Below Leaf Grade Cotton. Below leaf grade cotton is American Upland cotton which is lower in leaf grade than...

  12. 7 CFR 28.471 - Below Leaf Grade Cotton.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Below Leaf Grade Cotton. 28.471 Section 28.471... REGULATIONS COTTON CLASSING, TESTING, AND STANDARDS Standards Below Leaf Grade Cotton § 28.471 Below Leaf Grade Cotton. Below leaf grade cotton is American Upland cotton which is lower in leaf grade than...

  13. 7 CFR 28.471 - Below Leaf Grade Cotton.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 7 Agriculture 2 2014-01-01 2014-01-01 false Below Leaf Grade Cotton. 28.471 Section 28.471... REGULATIONS COTTON CLASSING, TESTING, AND STANDARDS Standards Below Leaf Grade Cotton § 28.471 Below Leaf Grade Cotton. Below leaf grade cotton is American Upland cotton which is lower in leaf grade than...

  14. Joint leaf chlorophyll and leaf area index retrieval using a regularized canopy reflectance model inversion system

    NASA Astrophysics Data System (ADS)

    Houborg, R.; McCabe, M. F.; Gitelson, A. A.

    2013-12-01

    Leaf area index (LAI) and leaf chlorophyll (Chl) represent key biophysical and biochemical controls on water, energy and carbon exchange processes in the terrestrial biosphere. In combination LAI and Chl provide critical information on vegetation density and phenology, the vitality of vegetation and photosynthetic functioning, and joint satellite-based retrievals can be used to inform land surface models and reduce uncertainties of model predicted ecosystem fluxes in space and time. Simultaneous retrieval of LAI and Chl from space observations is however extremely challenging as the interference of atmospheric effects, canopy characteristics and background reflectance may confound the detection of relatively subtle differences in canopy reflectance resulting from changes in Chl. Regularization strategies are therefore required to increase robustness and accuracy of retrieved properties and more reliably separate soil, leaf and canopy variables. Here we describe recent refinements to the REGularized canopy reFLECtance model (REGFLEC) retrieval system, which includes enhanced regularization techniques for exploiting ancillary LAI and temporal information derived from multiple satellite scenes over a given growing season. REGFLEC is applied to Landsat time-series data and retrieval results evaluated against in-situ LAI and Chl collected over maize and soybean sites in central Nebraska over a 5-year period (2001-2005). While REGFLEC may provide useful information on the density and vitality of vegetation, the results reflect the challenges associated with accurately extracting the relatively small leaf-level chlorophyll signal from the total satellite signal when using a few standard broad bands available operationally (i.e. blue, green, red and near-infrared) as input to a homogeneous canopy reflectance model. A noteworthy and novel aspect of the REGFLEC approach is the fact that no site-specific data were used to calibrate the model that may be run in a completely

  15. Measuring and modeling the backscattering cross section of a leaf

    NASA Technical Reports Server (NTRS)

    Senior, T. B. A.; Sarabandi, K.; Ulaby, F. T.

    1987-01-01

    Leaves are a significant feature of any vegetation canopy, and for remote sensing purposes it is important to develop an effective model for predicting the scattering from a leaf. From measurements of the X band backscattering cross section of a coleus leaf in varying stages of dryness, it is shown that a uniform resistive sheet constitutes such a model for a planar leaf. The scattering is determined by the (complex) resistivity which is, in turn, entirely specified by the gravimetric moisture content of the leaf. Using an available asymptotic expression for the scattering from a rectangular resistive plate which includes, as a special case, a metallic plate whose resistivity is zero, the computed backscattering cross sections for both principal polarizations are found to be in excellent agreement with data measured for rectangular sections of leaves with different moisture contents. If the resistivity is sufficiently large, the asymptotic expressions do not differ significantly from the physical optics ones, and for naturally shaped leaves as well as rectangular sections, the physical optics approximation in conjunction with the resistive sheet model faithfully reproduces the dominant feataures of the scattering patterns under all moisture conditions.

  16. Measuring and modeling the backscattering cross section of a leaf

    NASA Technical Reports Server (NTRS)

    Senior, T. B. A.; Sarabandi, K.; Ulaby, F. T.

    1987-01-01

    Leaves are a significant feature of any vegetation canopy, and for remote sensing purposes it is important to develop an effective model for predicting the scattering from a leaf. From measurements of the X band backscattering cross section of a coleus leaf in varying stages of dryness, it is shown that a uniform resistive sheet constitutes such a model for a planar leaf. The scattering is determined by the (complex) resistivity which is, in turn, entirely specified by the gravimetric moisture content of the leaf. Using an available asymptotic expression for the scattering from a rectangular resistive plate which includes, as a special case, a metallic plate whose resistivity is zero, the computed backscattering cross sections for both principal polarizations are found to be in excellent agreement with data measured for rectangular sections of leaves with different moisture contents. If the resistivity is sufficiently large, the asymptotic expressions do not differ significantly from the physical optics ones, and for naturally shaped leaves as well as rectangular sections, the physical optics approximation in conjunction with the resistive sheet model faithfully reproduces the dominant feataures of the scattering patterns under all moisture conditions.

  17. Spatial trends in leaf size of Amazonian rainforest trees

    NASA Astrophysics Data System (ADS)

    Malhado, A. C. M.; Malhi, Y.; Whittaker, R. J.; Ladle, R. J.; Ter Steege, H.; Phillips, O. L.; Butt, N.; Aragão, L. E. O. C.; Quesada, C. A.; Araujo-Murakami, A.; Arroyo, L.; Peacock, J.; Lopez-Gonzalez, G.; Baker, T. R.; Anderson, L. O.; Almeida, S.; Higuchi, N.; Killeen, T. J.; Monteagudo, A.; Neill, D.; Pitman, N.; Prieto, A.; Salomão, R. P.; Vásquez-Martínez, R.; Laurance, W. F.

    2009-08-01

    Leaf size influences many aspects of tree function such as rates of transpiration and photosynthesis and, consequently, often varies in a predictable way in response to environmental gradients. The recent development of pan-Amazonian databases based on permanent botanical plots has now made it possible to assess trends in leaf size across environmental gradients in Amazonia. Previous plot-based studies have shown that the community structure of Amazonian trees breaks down into at least two major ecological gradients corresponding with variations in soil fertility (decreasing from southwest to northeast) and length of the dry season (increasing from northwest to south and east). Here we describe the geographic distribution of leaf size categories based on 121 plots distributed across eight South American countries. We find that the Amazon forest is predominantly populated by tree species and individuals in the mesophyll size class (20.25-182.25 cm2). The geographic distribution of species and individuals with large leaves (>20.25 cm2) is complex but is generally characterized by a higher proportion of such trees in the northwest of the region. Spatially corrected regressions reveal weak correlations between the proportion of large-leaved species and metrics of water availability. We also find a significant negative relationship between leaf size and wood density.

  18. Correlated evolution of stem and leaf hydraulic traits in Pereskia (Cactaceae).

    PubMed

    Edwards, Erika J

    2006-01-01

    Recent studies have demonstrated significant correlations between stem and leaf hydraulic properties when comparing across species within ecological communities. This implies that these traits are co-evolving, but there have been few studies addressing plant water relations within an explicitly evolutionary framework. This study tests for correlated evolution among a suite of plant water-use traits and environmental parameters in seven species of Pereskia (Cactaceae), using phylogenetically independent contrasts. There were significant evolutionary correlations between leaf-specific xylem hydraulic conductivity, Huber Value, leaf stomatal pore index, leaf venation density and leaf size, but none of these traits appeared to be correlated with environmental water availability; only two water relations traits - mid-day leaf water potentials and photosynthetic water use efficiency - correlated with estimates of moisture regime. In Pereskia, it appears that many stem and leaf hydraulic properties thought to be critical to whole-plant water use have not evolved in response to habitat shifts in water availability. This may be because of the extremely conservative stomatal behavior and particular rooting strategy demonstrated by all Pereskia species investigated. These results highlight the need for a lineage-based approach to understand the relative roles of functional traits in ecological adaptation.

  19. Predicting tree water use and drought tolerance from leaf traits in the Los Angeles urban ecosystem

    NASA Astrophysics Data System (ADS)

    John, G. P.; Scoffoni, C.; Sack, L.

    2013-12-01

    Urban green space provides a suite of valuable ecosystem services. In semiarid systems, like Los Angeles, trees rely primarily on irrigation water for transpiration. Managers may need to reduce irrigation associated with urban trees given climate change, urban expansion, and the steady decrease in available freshwater. While leaf and whole plant water relations have been extensively studied, we are only now gaining a detailed understanding of diverse leaf anatomical designs, and their use for predicting physiology and water use at landscape scale. For 50 diverse urban species, we quantified leaf anatomical and physiological traits important to tree drought tolerance and water use efficiency including turgor loss point, vein architecture, cellular anatomy, leaf mass per unit area, and petiole and leaf dimensions. We hypothesized detailed relationships to develop models relating leaf functional traits to tree water relations. These models provide key insights regarding the role of anatomical designs in leaf stress tolerance and water use efficiency. Additionally we predicted how traits measured at the leaf level would scale with existing data for individuals at the whole plant level. We tested our predictions by determining correlations between leaf level anatomical traits and drought tolerance. Additionally, we determined correlations between functional traits, physiology and water use, and the climate of origin for the urban species. Leaf level measurements will be valuable for rapid estimation of more difficult to measure whole plant water relations traits important at the landscape scale. The Los Angeles urban ecosystem can serve as a model for other semiarid system and provide more informed system wide water conservation strategies.

  20. Carbon/Nitrogen Imbalance Associated with Drought-Induced Leaf Senescence in Sorghum bicolor

    PubMed Central

    Chen, Daoqian; Wang, Shiwen; Xiong, Binglin; Cao, Beibei; Deng, Xiping

    2015-01-01

    Drought stress triggers mature leaf senescence, which supports plant survival and remobilization of nutrients; yet leaf senescence also critically decreases post-drought crop yield. Drought generally results in carbon/nitrogen imbalance, which is reflected in the increased carbon:nitrogen (C:N) ratio in mature leaves, and which has been shown to be involved in inducing leaf senescence under normal growth conditions. Yet the involvement of the carbon/nitrogen balance in regulation of drought-induced leaf senescence is unclear. To investigate the role of carbon/nitrogen balance in drought-induced senescence, sorghum seedlings were subjected to a gradual soil drought treatment. Leaf senescence symptoms and the C:N ratio, which was indicated by the ratio of non-structural carbohydrate to total N content, were monitored during drought progression. In this study, leaf senescence developed about 12 days after the start of drought treatment, as indicated by various senescence symptoms including decreasing photosynthesis, photosystem II photochemistry efficiency (Fv/Fm) and chlorophyll content, and by the differential expression of senescence marker genes. The C:N ratio was significantly enhanced 10 to 12 days into drought treatment. Leaf senescence occurred in the older (lower) leaves, which had higher C:N ratios, but not in the younger (upper) leaves, which had lower C:N ratios. In addition, a detached leaf assay was conducted to investigate the effect of carbon/nitrogen availability on drought-induced senescence. Exogenous application of excess sugar combined with limited nitrogen promoted drought-induced leaf senescence. Thus our results suggest that the carbon/nitrogen balance may be involved in the regulation of drought-induced leaf senescence. PMID:26317421

  1. Carbon/Nitrogen Imbalance Associated with Drought-Induced Leaf Senescence in Sorghum bicolor.

    PubMed

    Chen, Daoqian; Wang, Shiwen; Xiong, Binglin; Cao, Beibei; Deng, Xiping

    2015-01-01

    Drought stress triggers mature leaf senescence, which supports plant survival and remobilization of nutrients; yet leaf senescence also critically decreases post-drought crop yield. Drought generally results in carbon/nitrogen imbalance, which is reflected in the increased carbon:nitrogen (C:N) ratio in mature leaves, and which has been shown to be involved in inducing leaf senescence under normal growth conditions. Yet the involvement of the carbon/nitrogen balance in regulation of drought-induced leaf senescence is unclear. To investigate the role of carbon/nitrogen balance in drought-induced senescence, sorghum seedlings were subjected to a gradual soil drought treatment. Leaf senescence symptoms and the C:N ratio, which was indicated by the ratio of non-structural carbohydrate to total N content, were monitored during drought progression. In this study, leaf senescence developed about 12 days after the start of drought treatment, as indicated by various senescence symptoms including decreasing photosynthesis, photosystem II photochemistry efficiency (Fv/Fm) and chlorophyll content, and by the differential expression of senescence marker genes. The C:N ratio was significantly enhanced 10 to 12 days into drought treatment. Leaf senescence occurred in the older (lower) leaves, which had higher C:N ratios, but not in the younger (upper) leaves, which had lower C:N ratios. In addition, a detached leaf assay was conducted to investigate the effect of carbon/nitrogen availability on drought-induced senescence. Exogenous application of excess sugar combined with limited nitrogen promoted drought-induced leaf senescence. Thus our results suggest that the carbon/nitrogen balance may be involved in the regulation of drought-induced leaf senescence.

  2. A cross-species transcriptomics approach to identify genes involved in leaf development

    PubMed Central

    Street, Nathaniel Robert; Sjödin, Andreas; Bylesjö, Max; Gustafsson, Petter; Trygg, Johan; Jansson, Stefan

    2008-01-01

    Background We have made use of publicly available gene expression data to identify transcription factors and transcriptional modules (regulons) associated with leaf development in Populus. Different tissue types were compared to identify genes informative in the discrimination of leaf and non-leaf tissues. Transcriptional modules within this set of genes were identified in a much wider set of microarray data collected from leaves in a number of developmental, biotic, abiotic and transgenic experiments. Results Transcription factors that were over represented in leaf EST libraries and that were useful for discriminating leaves from other tissues were identified, revealing that the C2C2-YABBY, CCAAT-HAP3 and 5, MYB, and ZF-HD families are particularly important in leaves. The expression of transcriptional modules and transcription factors was examined across a number of experiments to select those that were particularly active during the early stages of leaf development. Two transcription factors were found to collocate to previously published Quantitative Trait Loci (QTL) for leaf length. We also found that miRNA family 396 may be important in the control of leaf development, with three members of the family collocating with clusters of leaf development QTL. Conclusion This work provides a set of candidate genes involved in the control and processes of leaf development. This resource can be used for a wide variety of purposes such as informing the selection of candidate genes for association mapping or for the selection of targets for reverse genetics studies to further understanding of the genetic control of leaf size and shape. PMID:19061504

  3. Spatial patterns of leaf δ13C and its relationship with plant functional groups and environmental factors in China

    NASA Astrophysics Data System (ADS)

    Li, Mingxu; Peng, Changhui; Wang, Meng; Yang, Yanzheng; Zhang, Kerou; Li, Peng; Yang, Yan; Ni, Jian; Zhu, Qiuan

    2017-07-01

    The leaf carbon isotope ratio (δ13C) is a useful parameter for predicting a plant's water use efficiency, as an indicator for plant classification, and even in the reconstruction of paleoclimatic environments. In this study, we investigated the spatial pattern of leaf δ13C values and its relationship with plant functional groups and environmental factors throughout China. The high leaf δ13C in the database appeared in central and western China, and the averaged leaf δ13C was -27.15‰, with a range from -21.05‰ to -31.5‰. The order of the averaged δ13C for plant life forms from most positive to most negative was subshrubs > herbs = shrubs > trees > subtrees. Leaf δ13C is also influenced by some environmental factors, such as mean annual precipitation, relative humidity, mean annual temperature, solar hours, and altitude, although the overall influences are still relatively weak, in particular the influence of MAT and altitude. And we further found that plant functional types are dominant factors that regulate the magnitude of leaf δ13C for an individual site, whereas environmental conditions are key to understanding spatial patterns of leaf δ13C when we consider China as a whole. Ultimately, we conducted a multiple regression model of leaf δ13C with environmental factors and mapped the spatial distribution of leaf δ13C in China by using this model. However, this partial least squares model overestimated leaf δ13C for most life forms, especially for deciduous trees, evergreen shrubs, and subtrees, and thus need more improvement in the future.

  4. Drought effects on leaf abscission and leaf production in Populus clones

    Treesearch

    Stephen G. Pallardy; Julie L. Rhoads

    1997-01-01

    Leaf abscission and foliation responses to water stress were studied in potted plants of five Populus clones grown in a greenhouse. As predawn leaf water potential (Ψ1) fell to -3 MPa, drought-induced leaf abscission increased progressively to 30% for data pooled across clones. As predawn Ψ1...

  5. Prudent sperm use by leaf-cutter ant queens

    PubMed Central

    den Boer, Susanne P. A.; Baer, Boris; Dreier, Stephanie; Aron, Serge; Nash, David R.; Boomsma, Jacobus J.

    2009-01-01

    In many species, females store sperm between copulation and egg fertilization, but the consequences of sperm storage and patterns of sperm use for female life history and reproductive success have not been investigated in great detail. In hymenopteran insect societies (ants, bees, wasps), reproduction is usually monopolized by one or relatively few queens, who mate only during a brief period early in life and store sperm for later use. The queens of some ants are particularly long-lived and have the potential to produce millions of offspring during their life. To do so, queens store many sperm cells, and this sperm must remain viable throughout the years of storage. Queens should also be under strong selection to use stored sperm prudently when fertilizing eggs. We used the leaf-cutter ant Atta colombica to investigate the dynamics of sperm use during egg fertilization. We show that queens are able to fertilize close to 100 per cent of the eggs and that the average sperm use per egg is very low, but increases with queen age. The robustness of stored sperm was found to decrease with years of storage, signifying that senescence affects sperm either directly or indirectly via the declining glandular secretions or deteriorating sperm-storage organs. We evaluate our findings with a heuristic model, which suggests that the average queen has sperm for almost 9 years of normal colony development. We discuss the extent to which leaf-cutter ant queens have been able to optimize their sperm expenditure and infer that our observed averages of sperm number, sperm robustness and sperm use are consistent with sperm depletion being a significant cause of mortality of mature colonies of Atta leaf-cutter ants. PMID:19710057

  6. Prudent sperm use by leaf-cutter ant queens.

    PubMed

    den Boer, Susanne P A; Baer, Boris; Dreier, Stephanie; Aron, Serge; Nash, David R; Boomsma, Jacobus J

    2009-11-22

    In many species, females store sperm between copulation and egg fertilization, but the consequences of sperm storage and patterns of sperm use for female life history and reproductive success have not been investigated in great detail. In hymenopteran insect societies (ants, bees, wasps), reproduction is usually monopolized by one or relatively few queens, who mate only during a brief period early in life and store sperm for later use. The queens of some ants are particularly long-lived and have the potential to produce millions of offspring during their life. To do so, queens store many sperm cells, and this sperm must remain viable throughout the years of storage. Queens should also be under strong selection to use stored sperm prudently when fertilizing eggs. We used the leaf-cutter ant Atta colombica to investigate the dynamics of sperm use during egg fertilization. We show that queens are able to fertilize close to 100 per cent of the eggs and that the average sperm use per egg is very low, but increases with queen age. The robustness of stored sperm was found to decrease with years of storage, signifying that senescence affects sperm either directly or indirectly via the declining glandular secretions or deteriorating sperm-storage organs. We evaluate our findings with a heuristic model, which suggests that the average queen has sperm for almost 9 years of normal colony development. We discuss the extent to which leaf-cutter ant queens have been able to optimize their sperm expenditure and infer that our observed averages of sperm number, sperm robustness and sperm use are consistent with sperm depletion being a significant cause of mortality of mature colonies of Atta leaf-cutter ants.

  7. The effect of experimental warming on leaf functional traits, leaf structure and leaf biochemistry in Arabidopsis thaliana.

    PubMed

    Jin, Biao; Wang, Li; Wang, Jing; Jiang, Ke-Zhen; Wang, Yang; Jiang, Xiao-Xue; Ni, Cheng-Yang; Wang, Yu-Long; Teng, Nian-Jun

    2011-02-18

    The leaf is an important plant organ, and how it will respond to future global warming is a question that remains unanswered. The effects of experimental warming on leaf photosynthesis and respiration acclimation has been well studied so far, but relatively little information exists on the structural and biochemical responses to warming. However, such information is very important to better understand the plant responses to global warming. Therefore, we grew Arabidopsis thaliana at the three day/night temperatures of 23/18°C (ambient temperature), 25.5/20.5°C (elevated by 2.5°C) and 28/23°C (elevated by 5°C) to simulate the middle and the upper projected warming expected within the 21st century for this purpose. The 28/23°C treatment significantly reduced the life span, total biomass and total weight of seeds compared with the other two temperatures. Among the three temperature regimes, the concentrations of starch, chlorophyll, and proline were the lowest at 28/23°C, whereas the total weight of seeds, concentrations of chlorophyll and proline, stomatal density (SD), stomatal conductance (gs), net CO2 assimilation rate (A) and transpiration rate (E) were the highest at 25.5/20.5°C. Furthermore, the number of chloroplasts per cell and mitochondrial size were highest at 25.5/20.5°C and lowest at 28/23°C. The conditions whereby the temperature was increased by 2.5°C were advantageous for Arabidopsis. However, a rise of 5°C produced negative effects, suggesting that lower levels of warming may benefit plants, especially those which belong to the same functional group as Arabidopsis, whereas higher levels of warming may produce negative affects. In addition, the increase in A under moderately warm conditions may be attributed to the increase in SD, chlorophyll content, and number of chloroplasts. Furthermore, starch accumulation in chloroplasts may be the main factor influencing chloroplast ultrastructure, and elevated temperature regulates plant respiration

  8. Molecular Characterization of Tomato leaf curl Palampur virus and Pepper leaf curl betasatellite Naturally Infecting Pumpkin (Cucurbita moschata) in India.

    PubMed

    Namrata, Jaiswal; Saritha, R K; Datta, D; Singh, M; Dubey, R S; Rai, A B; Rai, M

    2010-10-01

    Pumpkin cultivation in India is affected by severe incidence of a yellow vein mosaic disease. Tomato leaf curl New Delhi virus and Squash leaf curl China virus are known to be associated with this disease in India. We were able to identify a third begomovirus-Tomato leaf curl Palampur virus (ToLCPMV), from pumpkin showing typical symptoms of the disease at Varanasi based on the sequence of complete DNA-A genome of the virus. The complete DNA-A sequence of the virus shared more than 99% sequence identity with other ToLCPMV isolates available in the GenBank and clustered with them in the phylogenetic analysis. This betasatellite amplified from the same infected sample has been identified as Pepper leaf curl betasatellite (PepLCB) which also infects chilli in India. There was 92% sequence identity between the two isolates. This is the first report of natural infection of ToLCPMV on pumpkin and association of PepLCB with yellow vein mosaic disease of pumpkin in India.

  9. Association of a recombinant Cotton leaf curl Bangalore virus with yellow vein and leaf curl disease of okra in India.

    PubMed

    Venkataravanappa, V; Lakshminarayana Reddy, C N; Devaraju, A; Jalali, Salil; Krishna Reddy, M

    2013-09-01

    A begomovirus isolate (OY136A) collected from okra plants showing upward leaf curling, vein clearing, vein thickening and yellowing symptoms from Bangalore rural district, Karnataka, India was characterized. The sequence comparisons revealed that, this virus isolate share highest nucleotide identity with isolates of Cotton leaf curl Bangalore virus (CLCuBV) (AY705380) (92.8 %) and Okra enation leaf curl virus (81.1-86.2 %). This is well supported by phylogentic analysis showing, close clustering of the virus isolate with CLCuBV. With this data, based on the current taxonomic criteria for the genus Begomovirus, the present virus isolate is classified as a new strain of CLCuBV, for which CLCuBV-[India: Bangalore: okra: 2006] additional descriptor is proposed. The betasatellite (KC608158) associated with the virus is having more than 95 % sequence similarity with the cotton leaf curl betasatellites (CLCuB) available in the GenBank.The recombination analysis suggested, emergence of this new strain of okra infecting begomovirus might have been from the exchange of genetic material between BYVMV and CLCuMuV. The virus was successfully transmitted by whitefly and grafting. The host range of the virus was shown to be very narrow and limited to two species in the family Malvaceae, okra (Abelmoschus esculentus) and hollyhock (Althaea rosea), and four in the family Solanaceae.

  10. Transpiration and Leaf Temperature. Physical Processes in Terrestrial and Aquatic Ecosystems, Transport Processes.

    ERIC Educational Resources Information Center

    Gates, David M.

    These materials were designed to be used by life science students for instruction in the application of physical theory to ecosystem operation. Most modules contain computer programs which are built around a particular application of a physical process. This report introduces two models of the thermal energy budget of a leaf. Typical values for…

  11. “Breath figures” on leaf surfaces—formation and effects of microscopic leaf wetness

    PubMed Central

    Burkhardt, Juergen; Hunsche, Mauricio

    2013-01-01

    “Microscopic leaf wetness” means minute amounts of persistent liquid water on leaf surfaces which are invisible to the naked eye. The water is mainly maintained by transpired water vapor condensing onto the leaf surface and to attached leaf surface particles. With an estimated average thickness of less than 1 μm, microscopic leaf wetness is about two orders of magnitude thinner than morning dewfall. The most important physical processes which reduce the saturation vapor pressure and promote condensation are cuticular absorption and the deliquescence of hygroscopic leaf surface particles. Deliquescent salts form highly concentrated solutions. Depending on the type and concentration of the dissolved ions, the physicochemical properties of microscopic leaf wetness can be considerably different from those of pure water. Microscopic leaf wetness can form continuous thin layers on hydrophobic leaf surfaces and in specific cases can act similar to surfactants, enabling a strong potential influence on the foliar exchange of ions. Microscopic leaf wetness can also enhance the dissolution, the emission, and the reaction of specific atmospheric trace gases e.g., ammonia, SO2, or ozone, leading to a strong potential role for microscopic leaf wetness in plant/atmosphere interaction. Due to its difficult detection, there is little knowledge about the occurrence and the properties of microscopic leaf wetness. However, based on the existing evidence and on physicochemical reasoning it can be hypothesized that microscopic leaf wetness occurs on almost any plant worldwide and often permanently, and that it significantly influences the exchange processes of the leaf surface with its neighboring compartments, i.e., the plant interior and the atmosphere. The omission of microscopic water in general leaf wetness concepts has caused far-reaching, misleading conclusions in the past. PMID:24167510

  12. "Breath figures" on leaf surfaces-formation and effects of microscopic leaf wetness.

    PubMed

    Burkhardt, Juergen; Hunsche, Mauricio

    2013-01-01

    "Microscopic leaf wetness" means minute amounts of persistent liquid water on leaf surfaces which are invisible to the naked eye. The water is mainly maintained by transpired water vapor condensing onto the leaf surface and to attached leaf surface particles. With an estimated average thickness of less than 1 μm, microscopic leaf wetness is about two orders of magnitude thinner than morning dewfall. The most important physical processes which reduce the saturation vapor pressure and promote condensation are cuticular absorption and the deliquescence of hygroscopic leaf surface particles. Deliquescent salts form highly concentrated solutions. Depending on the type and concentration of the dissolved ions, the physicochemical properties of microscopic leaf wetness can be considerably different from those of pure water. Microscopic leaf wetness can form continuous thin layers on hydrophobic leaf surfaces and in specific cases can act similar to surfactants, enabling a strong potential influence on the foliar exchange of ions. Microscopic leaf wetness can also enhance the dissolution, the emission, and the reaction of specific atmospheric trace gases e.g., ammonia, SO2, or ozone, leading to a strong potential role for microscopic leaf wetness in plant/atmosphere interaction. Due to its difficult detection, there is little knowledge about the occurrence and the properties of microscopic leaf wetness. However, based on the existing evidence and on physicochemical reasoning it can be hypothesized that microscopic leaf wetness occurs on almost any plant worldwide and often permanently, and that it significantly influences the exchange processes of the leaf surface with its neighboring compartments, i.e., the plant interior and the atmosphere. The omission of microscopic water in general leaf wetness concepts has caused far-reaching, misleading conclusions in the past.

  13. The leaf-area shrinkage effect can bias paleoclimate and ecology research.

    PubMed

    Blonder, Benjamin; Buzzard, Vanessa; Simova, Irena; Sloat, Lindsey; Boyle, Brad; Lipson, Rebecca; Aguilar-Beaucage, Brianna; Andrade, Angelina; Barber, Benjamin; Barnes, Chris; Bushey, Dharma; Cartagena, Paulina; Chaney, Max; Contreras, Karina; Cox, Mandarava; Cueto, Maya; Curtis, Cannon; Fisher, Mariah; Furst, Lindsey; Gallegos, Jessica; Hall, Ruby; Hauschild, Amelia; Jerez, Alex; Jones, Nadja; Klucas, Aaron; Kono, Anita; Lamb, Mary; Matthai, Jacob David Ruiz; McIntyre, Colten; McKenna, Joshua; Mosier, Nicholas; Navabi, Maya; Ochoa, Alex; Pace, Liam; Plassmann, Ryland; Richter, Rachel; Russakoff, Ben; Aubyn, Holden St; Stagg, Ryan; Sterner, Marley; Stewart, Emily; Thompson, Ting Ting; Thornton, Jake; Trujillo, Parker J; Volpe, Trevor J; Enquist, Brian J

    2012-11-01

    Leaf area is a key trait that links plant form, function, and environment. Measures of leaf area can be biased because leaf area is often estimated from dried or fossilized specimens that have shrunk by an unknown amount. We tested the common assumption that this shrinkage is negligible. We measured shrinkage by comparing dry and fresh leaf area in 3401 leaves of 380 temperate and tropical species and used phylogenetic and trait-based approaches to determine predictors of this shrinkage. We also tested the effects of rehydration and simulated fossilization on shrinkage in four species. We found that dried leaves shrink in area by an average of 22% and a maximum of 82%. Shrinkage in dried leaves can be predicted by multiple morphological traits with a standard deviation of 7.8%. We also found that mud burial, a proxy for compression fossilization, caused negligible shrinkage, and that rehydration, a potential treatment of dried herbarium specimens, eliminated shrinkage. Our findings indicate that the amount of shrinkage is driven by variation in leaf area, leaf thickness, evergreenness, and woodiness and can be reversed by rehydration. The amount of shrinkage may also be a useful trait related to ecologically and physiological differences in drought tolerance and plant life history.

  14. Dissipation and Residues of Pyrethrins in Leaf Lettuce under Greenhouse and Open Field Conditions

    PubMed Central

    Pan, Lixiang; Feng, Xiaoxiao; Zhang, Hongyan

    2017-01-01

    Pyrethrins are nowadays widely used for prevention and control of insects in leaf lettuce. However, there is a concern about the pesticide residue in leaf lettuce. A reliable analytical method for determination of pyrethrins (pyrethrin—and П, cinerin І and П, and jasmolin І and П) in leaf lettuce was developed by using gas chromatography–mass spectrometry (GC–MS). Recoveries of pyrethrins in leaf lettuce at three spiking levels were 99.4–104.0% with relative standard deviations of 0.9–3.1% (n = 5). Evaluation of dissipation and final residues of pyrethrins in leaf lettuce were determined at six different locations, including the open field, as well as under greenhouse conditions. The initial concentration of pyrethrins in greenhouse (0.57 mg/kg) was higher than in open field (0.25 mg/kg) and the half-life for pyrethrins disappearance in field lettuce (0.7 days) was less than that greenhouse lettuce (1.1 days). Factors such as rainfall, solar radiation, wind speed, and crop growth rate are likely to have caused these results. The final residue in leaf lettuce was far below the maximum residue limits (MRLs) (1 mg/kg established by the European Union (EU), Australia, Korea, Japan). PMID:28754023

  15. Compensatory responses in plant-herbivore interactions: Impacts of insects on leaf water relations

    NASA Astrophysics Data System (ADS)

    Peschiutta, María L.; Bucci, Sandra J.; Scholz, Fabián G.; Goldstein, Guillermo

    2016-05-01

    Herbivore damage to leaves has been typically evaluated in terms of fractions of area removed; however morpho-physiological changes in the remaining tissues can occur in response to removal. We assessed the effects of partial removal of the leaf mesophyll by Caliroa cerasi (Hymenoptera) on leaf hydraulic conductance (Kleaf), vascular architecture, water relations and leaf size of three Prunus avium cultivars. The insect feeds on the leaf mesophyll leaving the vein network intact (skeletonization). Within each cultivar there were trees without infestations and trees chronically infested, at least over the last three years. Leaf size of intact leaves tended to be similar during leaf expansion before herbivore attack occurs across infested and non-infested trees. However, after herbivore attack and when the leaves were fully expanded, damaged leaves were smaller than leaves from non-infested trees. Damaged area varied between 21 and 31% depending on cultivar. The non-disruption of the vascular system together with either vein density or capacitance increased in damaged leaves resulted in similar Kleaf and stomatal conductance in infested and non-infested trees. Non-stomatal water loss from repeated leaf damage led to lower leaf water potentials in two of the infested cultivars. Lower leaf osmotic potentials and vulnerability to loss of Kleaf were observed in infested plants. Our results show that skeletonization resulted in compensatory changes in terms of water relations and hydraulics traits and in cultivar-specific physiological changes in phylogenetic related P. avium. Our findings indicate that detrimental effects of herbivory on the photosynthetic surface are counterbalanced by changes providing higher drought resistance, which has adaptive significance in ecosystems where water availability is low and furthermore where global climate changes would decrease soil water availability in the future even further.

  16. Drought-Induced Leaf Proteome Changes in Switchgrass Seedlings

    PubMed Central

    Ye, Zhujia; Sangireddy, Sasikiran; Okekeogbu, Ikenna; Zhou, Suping; Yu, Chih-Li; Hui, Dafeng; Howe, Kevin J.; Fish, Tara; Thannhauser, Theodore W.

    2016-01-01

    Switchgrass (Panicum virgatum) is a perennial crop producing deep roots and thus highly tolerant to soil water deficit conditions. However, seedling establishment in the field is very susceptible to prolonged and periodic drought stress. In this study, a “sandwich” system simulating a gradual water deletion process was developed. Switchgrass seedlings were subjected to a 20-day gradual drought treatment process when soil water tension was increased to 0.05 MPa (moderate drought stress) and leaf physiological properties had expressed significant alteration. Drought-induced changes in leaf proteomes were identified using the isobaric tags for relative and absolute quantitation (iTRAQ) labeling method followed by nano-scale liquid chromatography mass spectrometry (nano-LC-MS/MS) analysis. Additionally, total leaf proteins were processed using a combinatorial library of peptide ligands to enrich for lower abundance proteins. Both total proteins and those enriched samples were analyzed to increase the coverage of the quantitative proteomics analysis. A total of 7006 leaf proteins were identified, and 257 (4% of the leaf proteome) expressed a significant difference (p < 0.05, fold change <0.6 or >1.7) from the non-treated control to drought-treated conditions. These proteins are involved in the regulation of transcription and translation, cell division, cell wall modification, phyto-hormone metabolism and signaling transduction pathways, and metabolic pathways of carbohydrates, amino acids, and fatty acids. A scheme of abscisic acid (ABA)-biosynthesis and ABA responsive signal transduction pathway was reconstructed using these drought-induced significant proteins, showing systemic regulation at protein level to deploy the respective mechanism. Results from this study, in addition to revealing molecular responses to drought stress, provide a large number of proteins (candidate genes) that can be employed to improve switchgrass seedling growth and establishment under

  17. Drought-Induced Leaf Proteome Changes in Switchgrass Seedlings.

    PubMed

    Ye, Zhujia; Sangireddy, Sasikiran; Okekeogbu, Ikenna; Zhou, Suping; Yu, Chih-Li; Hui, Dafeng; Howe, Kevin J; Fish, Tara; Thannhauser, Theodore W

    2016-08-02

    Switchgrass (Panicum virgatum) is a perennial crop producing deep roots and thus highly tolerant to soil water deficit conditions. However, seedling establishment in the field is very susceptible to prolonged and periodic drought stress. In this study, a "sandwich" system simulating a gradual water deletion process was developed. Switchgrass seedlings were subjected to a 20-day gradual drought treatment process when soil water tension was increased to 0.05 MPa (moderate drought stress) and leaf physiological properties had expressed significant alteration. Drought-induced changes in leaf proteomes were identified using the isobaric tags for relative and absolute quantitation (iTRAQ) labeling method followed by nano-scale liquid chromatography mass spectrometry (nano-LC-MS/MS) analysis. Additionally, total leaf proteins were processed using a combinatorial library of peptide ligands to enrich for lower abundance proteins. Both total proteins and those enriched samples were analyzed to increase the coverage of the quantitative proteomics analysis. A total of 7006 leaf proteins were identified, and 257 (4% of the leaf proteome) expressed a significant difference (p < 0.05, fold change <0.6 or >1.7) from the non-treated control to drought-treated conditions. These proteins are involved in the regulation of transcription and translation, cell division, cell wall modification, phyto-hormone metabolism and signaling transduction pathways, and metabolic pathways of carbohydrates, amino acids, and fatty acids. A scheme of abscisic acid (ABA)-biosynthesis and ABA responsive signal transduction pathway was reconstructed using these drought-induced significant proteins, showing systemic regulation at protein level to deploy the respective mechanism. Results from this study, in addition to revealing molecular responses to drought stress, provide a large number of proteins (candidate genes) that can be employed to improve switchgrass seedling growth and establishment under soil

  18. 7 CFR 29.2530 - Leaf structure.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ...-Cured Tobacco (u.s. Types 22, 23, and Foreign Type 96) § 29.2530 Leaf structure. The cell development of... 7 Agriculture 2 2011-01-01 2011-01-01 false Leaf structure. 29.2530 Section 29.2530 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing...

  19. 7 CFR 29.2278 - Leaf structure.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... structure. The cell development of a leaf as indicated by its porosity. (See chart, § 29.2351.) ... 7 Agriculture 2 2013-01-01 2013-01-01 false Leaf structure. 29.2278 Section 29.2278 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing...

  20. 7 CFR 29.2278 - Leaf structure.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... structure. The cell development of a leaf as indicated by its porosity. (See chart, § 29.2351.) ... 7 Agriculture 2 2011-01-01 2011-01-01 false Leaf structure. 29.2278 Section 29.2278 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing...

  1. 7 CFR 29.2278 - Leaf structure.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... structure. The cell development of a leaf as indicated by its porosity. (See chart, § 29.2351.) ... 7 Agriculture 2 2010-01-01 2010-01-01 false Leaf structure. 29.2278 Section 29.2278 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing...

  2. 7 CFR 29.2530 - Leaf structure.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ...-Cured Tobacco (u.s. Types 22, 23, and Foreign Type 96) § 29.2530 Leaf structure. The cell development of... 7 Agriculture 2 2013-01-01 2013-01-01 false Leaf structure. 29.2530 Section 29.2530 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing...

  3. 7 CFR 29.2278 - Leaf structure.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... structure. The cell development of a leaf as indicated by its porosity. (See chart, § 29.2351.) ... 7 Agriculture 2 2014-01-01 2014-01-01 false Leaf structure. 29.2278 Section 29.2278 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing...

  4. 7 CFR 29.2278 - Leaf structure.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... structure. The cell development of a leaf as indicated by its porosity. (See chart, § 29.2351.) ... 7 Agriculture 2 2012-01-01 2012-01-01 false Leaf structure. 29.2278 Section 29.2278 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing...

  5. 7 CFR 29.2530 - Leaf structure.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ...-Cured Tobacco (u.s. Types 22, 23, and Foreign Type 96) § 29.2530 Leaf structure. The cell development of... 7 Agriculture 2 2012-01-01 2012-01-01 false Leaf structure. 29.2530 Section 29.2530 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing...

  6. 7 CFR 29.2530 - Leaf structure.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ...-Cured Tobacco (u.s. Types 22, 23, and Foreign Type 96) § 29.2530 Leaf structure. The cell development of... 7 Agriculture 2 2010-01-01 2010-01-01 false Leaf structure. 29.2530 Section 29.2530 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing...

  7. 7 CFR 29.2530 - Leaf structure.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ...-Cured Tobacco (u.s. Types 22, 23, and Foreign Type 96) § 29.2530 Leaf structure. The cell development of... 7 Agriculture 2 2014-01-01 2014-01-01 false Leaf structure. 29.2530 Section 29.2530 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing...

  8. 7 CFR 29.1029 - Leaf scrap.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 7 Agriculture 2 2013-01-01 2013-01-01 false Leaf scrap. 29.1029 Section 29.1029 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing... Type 92) § 29.1029 Leaf scrap. A byproduct of stemmed and unstemmed tobacco. ...

  9. 7 CFR 29.1029 - Leaf scrap.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 7 Agriculture 2 2012-01-01 2012-01-01 false Leaf scrap. 29.1029 Section 29.1029 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing... Type 92) § 29.1029 Leaf scrap. A byproduct of stemmed and unstemmed tobacco. [42 FR 21092, Apr. 25...

  10. 7 CFR 29.1029 - Leaf scrap.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 7 Agriculture 2 2014-01-01 2014-01-01 false Leaf scrap. 29.1029 Section 29.1029 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing... Type 92) § 29.1029 Leaf scrap. A byproduct of stemmed and unstemmed tobacco. ...

  11. Leaf Histology--Two Modern Methods.

    ERIC Educational Resources Information Center

    Freeman, H. E.

    1984-01-01

    Two methods for examining leaf structure are presented; both methods involve use of "superglue." The first method uses the glue to form a thin, permanent, direct replica of a leaf surface on a microscope slide. The second method uses the glue to examine the three-dimensional structure of spongy mesophyll. (JN)

  12. 7 CFR 29.2277 - Leaf scrap.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Leaf scrap. 29.2277 Section 29.2277 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing... scrap. A byproduct of unstemmed tobacco. Leaf scrap results from handling unstemmed tobacco and consists...

  13. 7 CFR 29.2277 - Leaf scrap.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 7 Agriculture 2 2011-01-01 2011-01-01 false Leaf scrap. 29.2277 Section 29.2277 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing... scrap. A byproduct of unstemmed tobacco. Leaf scrap results from handling unstemmed tobacco and consists...

  14. 7 CFR 29.1029 - Leaf scrap.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 7 Agriculture 2 2011-01-01 2011-01-01 false Leaf scrap. 29.1029 Section 29.1029 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing... Type 92) § 29.1029 Leaf scrap. A byproduct of stemmed and unstemmed tobacco. [42 FR 21092, Apr. 25...

  15. 7 CFR 29.1029 - Leaf scrap.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Leaf scrap. 29.1029 Section 29.1029 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing... Type 92) § 29.1029 Leaf scrap. A byproduct of stemmed and unstemmed tobacco. [42 FR 21092, Apr. 25...

  16. Leaf Histology--Two Modern Methods.

    ERIC Educational Resources Information Center

    Freeman, H. E.

    1984-01-01

    Two methods for examining leaf structure are presented; both methods involve use of "superglue." The first method uses the glue to form a thin, permanent, direct replica of a leaf surface on a microscope slide. The second method uses the glue to examine the three-dimensional structure of spongy mesophyll. (JN)

  17. [Study on pharmacognosy of Ginkgo leaf].

    PubMed

    Geng, Guo-Ping; Ma, Zhi-Gang; Mao, Chong-Wu

    2007-05-01

    The primary study of Ginkgo leaf such as crude drug macroscopic and powder characteristics were carried out, and the flavonoids content in the leaf of Ginkgo in different areas of Gansu province was determined by HPLC, in order to provide scientific references for the exploitation of Ginkgo in Gansu province.

  18. Variation in essential oil composition within individual leaves of sweet basil (Ocimum basilicum L.) is more affected by leaf position than by leaf age.

    PubMed

    Fischer, Ravit; Nitzan, Nadav; Chaimovitsh, David; Rubin, Baruch; Dudai, Nativ

    2011-05-11

    The aroma in sweet basil is a factor affecting the commercial value of the crop. In previous studies leaf age was considered to be a factor that influences the composition of essential oil (EO). In this study it was hypothesized that a single observation of the EO content in leaves from different positions on the main stem (young vs old) could predict the developmental changes in the plant during its life cycle. Plants harvested at week 16 demonstrated an exponential increase (R(2) = 0.92) in EO concentration in leaves on the main stem and lateral shoots, indicating higher EO concentrations in younger than in older leaves. Eugenol and methyleugenol predominated (28-77%) in the extract. Eugenol levels were higher in younger leaves (∼53%), and methyl-eugenol levels predominated in older leaves (∼68%). Linalool was lower in mature leaves than in younger leaves. This suggested that eugenol converted into methyleugenol and linalool decreased as leaf mature. However, in weekly monitored plants, the levels of these compounds in the EO had limited variation in the maturing leaf regardless of its position on the stem. This proposed that the EO composition in an individual leaf is mostly affected by the leaf position on the stem and not by its maturation process. Because leaf position is related to plant development, it is probable that the plant's physiological age at the time of leaf formation from the primordial tissue is the factor affecting the EO composition. It was concluded that interpretation of scientific observations should be carried out with caution and that hypotheses should be tested utilizing multifaceted approaches.

  19. Relationships Between Photosynthetic Activity and Silica Accumulation with Ages of Leaf in Sasa veitchii (Poaceae, Bambusoideae)

    PubMed Central

    Motomura, Hiroyuki; Hikosaka, Kouki; Suzuki, Mitsuo

    2008-01-01

    Background and Aims Bamboos have long-lived, evergreen leaves that continue to accumulate silica throughout their life. Silica accumulation has been suggested to suppress their photosynthetic activity. However, nitrogen content per unit leaf area (Narea), an important determinant of maximum photosynthetic capacity per unit leaf area (Pmax), decreases as leaves age and senescence. In many species, Pmax decreases in parallel with the leaf nitrogen content. It is hypothesized that if silica accumulation affects photosynthesis, then Pmax would decrease faster than Narea, leading to a decrease in photosynthetic rate per unit leaf nitrogen (photosynthetic nitrogen use efficiency, PNUE) with increasing silica content in leaves. Methods The hypothesis was tested in leaves of Sasa veitchii, which have a life span of 2 years and accumulate silica up to 41 % of dry mass. Seasonal changes in Pmax, stomatal conductance, Narea and silica content were measured for leaves of different ages. Key Results Although Pmax and PNUE were negatively related with silica content across leaves of different ages, the relationship between PNUE and silica differed depending on leaf age. In second-year leaves, PNUE was almost constant although there was a large increase in silica content, suggesting that leaf nitrogen was a primary factor determining the variation in Pmax and that silica accumulation did not affect photosynthesis. PNUE was strongly and negatively correlated with silica content in third-year leaves, suggesting that silica accumulation affected photosynthesis of older leaves. Conclusions Silica accumulation in long-lived leaves of bamboo did not affect photosynthesis when the silica concentration of a leaf was less than 25 % of dry mass. Silica may be actively transported to epidermal cells rather than chlorenchyma cells, avoiding inhibition of CO2 diffusion from the intercellular space to chloroplasts. However, in older leaves with a larger silica content, silica was also

  20. Easy Leaf Area: Automated digital image analysis for rapid and accurate measurement of leaf area1

    PubMed Central

    Easlon, Hsien Ming; Bloom, Arnold J.

    2014-01-01

    • Premise of the study: Measurement of leaf areas from digital photographs has traditionally required significant user input unless backgrounds are carefully masked. Easy Leaf Area was developed to batch process hundreds of Arabidopsis rosette images in minutes, removing background artifacts and saving results to a spreadsheet-ready CSV file. • Methods and Results: Easy Leaf Area uses the color ratios of each pixel to distinguish leaves and calibration areas from their background and compares leaf pixel counts to a red calibration area to eliminate the need for camera distance calculations or manual ruler scale measurement that other software methods typically require. Leaf areas estimated by this software from images taken with a camera phone were more accurate than ImageJ estimates from flatbed scanner images. • Conclusions: Easy Leaf Area provides an easy-to-use method for rapid measurement of leaf area and nondestructive estimation of canopy area from digital images. PMID:25202639